[Kernel-packages] [Bug 1934175] Re: Kernel oops due to uninitialized list on kernfs (kernfs_kill_sb)
This bug was fixed in the package linux - 4.15.0-154.161 --- linux (4.15.0-154.161) bionic; urgency=medium * bionic/linux: 4.15.0-154.161 -proposed tracker (LP: #1938411) * Potential reverts of 4.19.y stable changes in 18.04 (LP: #1938537) - SAUCE: Revert "locking/mutex: clear MUTEX_FLAGS if wait_list is empty due to signal" - SAUCE: Revert "drm/amd/amdgpu: fix refcount leak" * Packaging resync (LP: #1786013) - [Packaging] resync getabis - [Packaging] update helper scripts - update dkms package versions * btrfs: Automatic balance returns -EUCLEAN and leads to forced readonly filesystem (LP: #1934709) // CVE-2019-19036 - btrfs: Validate child tree block's level and first key - btrfs: Detect unbalanced tree with empty leaf before crashing btree operations * btrfs: Automatic balance returns -EUCLEAN and leads to forced readonly filesystem (LP: #1934709) - Revert "btrfs: Detect unbalanced tree with empty leaf before crashing btree operations" - Revert "btrfs: Validate child tree block's level and first key" - btrfs: Only check first key for committed tree blocks - btrfs: Fix wrong first_key parameter in replace_path * Enable fib-onlink-tests.sh and msg_zerocopy.sh in kselftests/net on Bionic (LP: #1934759) - selftests: Add fib-onlink-tests.sh to TEST_PROGS - selftests: net: use TEST_PROGS_EXTENDED - selftests/net: enable msg_zerocopy test - SAUCE: selftests: Make fib-onlink-tests.sh executable * Kernel oops due to uninitialized list on kernfs (kernfs_kill_sb) (LP: #1934175) - kernfs: deal with kernfs_fill_super() failures - unfuck sysfs_mount() * large_dir in ext4 broken (LP: #1933074) - SAUCE: ext4: fix directory index node split corruption * btrfs: Attempting to balance a nearly full filesystem with relocated root nodes fails (LP: #1933172) // CVE-2019-19036 - btrfs: reloc: fix reloc root leak and NULL pointer dereference * btrfs: Attempting to balance a nearly full filesystem with relocated root nodes fails (LP: #1933172) - Revert "btrfs: reloc: fix reloc root leak and NULL pointer dereference" * Pixel format change broken for Elgato Cam Link 4K (LP: #1932367) - (upstream) media: uvcvideo: Fix pixel format change for Elgato Cam Link 4K * Bionic update: upstream stable patchset 2021-06-23 (LP: #1933375) - net: usb: cdc_ncm: don't spew notifications - efi: Allow EFI_MEMORY_XP and EFI_MEMORY_RO both to be cleared - efi: cper: fix snprintf() use in cper_dimm_err_location() - vfio/pci: Fix error return code in vfio_ecap_init() - vfio/pci: zap_vma_ptes() needs MMU - vfio/platform: fix module_put call in error flow - ipvs: ignore IP_VS_SVC_F_HASHED flag when adding service - HID: pidff: fix error return code in hid_pidff_init() - HID: i2c-hid: fix format string mismatch - netfilter: nfnetlink_cthelper: hit EBUSY on updates if size mismatches - ieee802154: fix error return code in ieee802154_add_iface() - ieee802154: fix error return code in ieee802154_llsec_getparams() - Bluetooth: fix the erroneous flush_work() order - Bluetooth: use correct lock to prevent UAF of hdev object - net: caif: added cfserl_release function - net: caif: add proper error handling - net: caif: fix memory leak in caif_device_notify - net: caif: fix memory leak in cfusbl_device_notify - ALSA: timer: Fix master timer notification - ext4: fix bug on in ext4_es_cache_extent as ext4_split_extent_at failed - pid: take a reference when initializing `cad_pid` - ocfs2: fix data corruption by fallocate - nfc: fix NULL ptr dereference in llcp_sock_getname() after failed connect - btrfs: fix error handling in btrfs_del_csums - btrfs: fixup error handling in fixup_inode_link_counts - mm, hugetlb: fix simple resv_huge_pages underflow on UFFDIO_COPY - selftests/bpf: make 'dubious pointer arithmetic' test useful - bnxt_en: Remove the setting of dev_port. - KVM: SVM: Truncate GPR value for DR and CR accesses in !64-bit mode - sched/fair: Optimize select_idle_cpu - xen-pciback: redo VF placement in the virtual topology - ALSA: usb: update old-style static const declaration - nl80211: validate key indexes for cfg80211_registered_device - x86/apic: Mark _all_ legacy interrupts when IO/APIC is missing - btrfs: return errors from btrfs_del_csums in cleanup_ref_head - KVM: arm64: Fix debug register indexing -- Kleber Sacilotto de Souza Fri, 30 Jul 2021 14:39:24 +0200 ** Changed in: linux (Ubuntu Bionic) Status: Fix Committed => Fix Released ** CVE added: https://cve.mitre.org/cgi-bin/cvename.cgi?name=2019-19036 -- You received this bug notification because you are a member of Kernel Packages, which is subscribed to linux in Ubuntu. https://bugs.launchpad.net/bugs/1934175 Title: Kernel oops due to uninitialized list on kernfs
[Kernel-packages] [Bug 1934175] Re: Kernel oops due to uninitialized list on kernfs (kernfs_kill_sb)
** Tags removed: verification-needed-bionic
** Tags added: bionic verification-done-bionic
--
You received this bug notification because you are a member of Kernel
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https://bugs.launchpad.net/bugs/1934175
Title:
Kernel oops due to uninitialized list on kernfs (kernfs_kill_sb)
Status in linux package in Ubuntu:
In Progress
Status in linux source package in Bionic:
Fix Committed
Bug description:
[Impact]
* We had a recent report of a kernel crash due to a NULL pointer dereference
in a Bionic 4.15 derivative kernel, as per the following log collected:
[...]
[537105.767348] SLUB: Unable to allocate memory on node -1,
gfp=0x14000c0(GFP_KERNEL)
[...]
[537105.767368] BUG: unable to handle kernel NULL pointer dereference at
0008
[537105.11] IP: kernfs_kill_sb+0x31/0x70
[537105.783582] PGD 0 P4D 0
[537105.787844] Oops: 0002 [#1] SMP PTI
[...]
RIP: 0010:kernfs_kill_sb+0x31/0x70
RSP: 0018:b90aec1afd00 EFLAGS: 00010286
RAX: RBX: 9fdbd567d900 RCX: a0143885ae01
RDX: RSI: a0143885ae00 RDI: a2937c40
RBP: b90aec1afd10 R08: a0150b581510 R09: 0001814d
R10: b90aec1afcd8 R11: 0100 R12: a01436e43000
R13: a01436e43000 R14: R15: 9fdbd567d900
FS: 7fe41a615b80() GS:a01afea4() knlGS:
CS: 0010 DS: ES: CR0: 80050033
CR2: 0008 CR3: 007dfe3cc003 CR4: 003606e0
DR0: DR1: DR2:
DR3: DR6: fffe0ff0 DR7: 0400
Call Trace:
sysfs_kill_sb+0x1f/0x40
deactivate_locked_super+0x48/0x80
kernfs_mount_ns+0x1eb/0x230
sysfs_mount+0x66/0xc0
mount_fs+0x37/0x160
? alloc_vfsmnt+0x1b3/0x230
vfs_kern_mount.part.24+0x5d/0x110
do_mount+0x5ed/0xce0
[...]
* The following detailed call stack plus the disassembly help to
understand the cause of the issue:
mount_fs()
--sysfs_mount()
kernfs_mount_ns()
--deactivate_locked_super()
sysfs_kill_sb()
--kernfs_kill_sb()
The below disassembly of kernfs_kill_sb() clarifies exactly the issue:
812f46e0 :
[ ... prologue ...]
48 8b 9f 08 04 00 00mov0x408(%rdi),%rbx # %rbx = kernfs_super_info
*info = sb->s_fs_info
49 89 fcmov%rdi,%r12 # %r12 = super_block *sb
48 c7 c7 40 7c 53 82mov$0x82537c40,%rdi # %rdi =
_mutex (global)
812f46f9: R_X86_64_32S kernfs_mutex
e8 ee da 67 00 callq 819721f0 #
mutex_lock(_mutex);
[...]
48 8b 53 18 mov0x18(%rbx),%rdx # %rdx = info->node
48 8b 43 20 mov0x20(%rbx),%rax # based on splat, RAX == 0x0
[info->head.prev]
48 89 42 08 mov%rax,0x8(%rdx) # <- OOPS [tried to assign
next->prev = prev, see __list_del()]
48 89 10mov%rdx,(%rax)
48 b8 00 01 00 00 00movabs $0xdead0100,%rax # node->next =
LIST_POISON1
[...]
* The fix for this issue comes from upstream commit 82382acec0c9
("kernfs: deal with kernfs_fill_super() failures"); this commit is a
very trivial fix that adds an INIT_LIST_HEAD(>node) in
kernfs_mount_ns(), making the list prev/next pointers valid since the
beginning. Unfortunately this commit wasn't CCed to stable email when
sent, so it wasn't automatically picked up by Ubuntu kernel; now it
was properly submitted to stable list [0].
* Along with this fix, we found another commit (7b745a4e4051) which is
a small/simple fix to correlated code, that also should have been sent
to 4.14.y stable branch, but for some reason wasn't. Since both
commits were accepted in linux-stable, we are hereby proposing the
backport for Ubuntu kernel 4.15.
[0]
https://lore.kernel.org/stable/20210622210622.9925-1-gpicc...@canonical.com/
[Test Case]
* We don't have a real test case, although low-memory condition or an
artificial kprobe reproducer could easily trigger the issue.
* We booted a qemu virtual machine with a kernel containing both
patches with no issues.
[Where problems could occur]
* The likelihood of issues are low, specially due to the fact both patches
are very simple and they are on upstream kernel for more than 3 years (and were
quickly accepted in 4.14.y stable branch last week).
* With that sad, the second patch could potentially introduce issues
with super_block references - I honestly cannot conceive any issues
potentially caused by patch 1.
To manage notifications about this bug go to:
https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1934175/+subscriptions
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[Kernel-packages] [Bug 1934175] Re: Kernel oops due to uninitialized list on kernfs (kernfs_kill_sb)
** Changed in: linux (Ubuntu)
Assignee: Guilherme G. Piccoli (gpiccoli) => (unassigned)
** Changed in: linux (Ubuntu Bionic)
Assignee: Guilherme G. Piccoli (gpiccoli) => (unassigned)
** Changed in: linux (Ubuntu Bionic)
Assignee: (unassigned) => Krzysztof Kozlowski (krzk)
--
You received this bug notification because you are a member of Kernel
Packages, which is subscribed to linux in Ubuntu.
https://bugs.launchpad.net/bugs/1934175
Title:
Kernel oops due to uninitialized list on kernfs (kernfs_kill_sb)
Status in linux package in Ubuntu:
In Progress
Status in linux source package in Bionic:
Fix Committed
Bug description:
[Impact]
* We had a recent report of a kernel crash due to a NULL pointer dereference
in a Bionic 4.15 derivative kernel, as per the following log collected:
[...]
[537105.767348] SLUB: Unable to allocate memory on node -1,
gfp=0x14000c0(GFP_KERNEL)
[...]
[537105.767368] BUG: unable to handle kernel NULL pointer dereference at
0008
[537105.11] IP: kernfs_kill_sb+0x31/0x70
[537105.783582] PGD 0 P4D 0
[537105.787844] Oops: 0002 [#1] SMP PTI
[...]
RIP: 0010:kernfs_kill_sb+0x31/0x70
RSP: 0018:b90aec1afd00 EFLAGS: 00010286
RAX: RBX: 9fdbd567d900 RCX: a0143885ae01
RDX: RSI: a0143885ae00 RDI: a2937c40
RBP: b90aec1afd10 R08: a0150b581510 R09: 0001814d
R10: b90aec1afcd8 R11: 0100 R12: a01436e43000
R13: a01436e43000 R14: R15: 9fdbd567d900
FS: 7fe41a615b80() GS:a01afea4() knlGS:
CS: 0010 DS: ES: CR0: 80050033
CR2: 0008 CR3: 007dfe3cc003 CR4: 003606e0
DR0: DR1: DR2:
DR3: DR6: fffe0ff0 DR7: 0400
Call Trace:
sysfs_kill_sb+0x1f/0x40
deactivate_locked_super+0x48/0x80
kernfs_mount_ns+0x1eb/0x230
sysfs_mount+0x66/0xc0
mount_fs+0x37/0x160
? alloc_vfsmnt+0x1b3/0x230
vfs_kern_mount.part.24+0x5d/0x110
do_mount+0x5ed/0xce0
[...]
* The following detailed call stack plus the disassembly help to
understand the cause of the issue:
mount_fs()
--sysfs_mount()
kernfs_mount_ns()
--deactivate_locked_super()
sysfs_kill_sb()
--kernfs_kill_sb()
The below disassembly of kernfs_kill_sb() clarifies exactly the issue:
812f46e0 :
[ ... prologue ...]
48 8b 9f 08 04 00 00mov0x408(%rdi),%rbx # %rbx = kernfs_super_info
*info = sb->s_fs_info
49 89 fcmov%rdi,%r12 # %r12 = super_block *sb
48 c7 c7 40 7c 53 82mov$0x82537c40,%rdi # %rdi =
_mutex (global)
812f46f9: R_X86_64_32S kernfs_mutex
e8 ee da 67 00 callq 819721f0 #
mutex_lock(_mutex);
[...]
48 8b 53 18 mov0x18(%rbx),%rdx # %rdx = info->node
48 8b 43 20 mov0x20(%rbx),%rax # based on splat, RAX == 0x0
[info->head.prev]
48 89 42 08 mov%rax,0x8(%rdx) # <- OOPS [tried to assign
next->prev = prev, see __list_del()]
48 89 10mov%rdx,(%rax)
48 b8 00 01 00 00 00movabs $0xdead0100,%rax # node->next =
LIST_POISON1
[...]
* The fix for this issue comes from upstream commit 82382acec0c9
("kernfs: deal with kernfs_fill_super() failures"); this commit is a
very trivial fix that adds an INIT_LIST_HEAD(>node) in
kernfs_mount_ns(), making the list prev/next pointers valid since the
beginning. Unfortunately this commit wasn't CCed to stable email when
sent, so it wasn't automatically picked up by Ubuntu kernel; now it
was properly submitted to stable list [0].
* Along with this fix, we found another commit (7b745a4e4051) which is
a small/simple fix to correlated code, that also should have been sent
to 4.14.y stable branch, but for some reason wasn't. Since both
commits were accepted in linux-stable, we are hereby proposing the
backport for Ubuntu kernel 4.15.
[0]
https://lore.kernel.org/stable/20210622210622.9925-1-gpicc...@canonical.com/
[Test Case]
* We don't have a real test case, although low-memory condition or an
artificial kprobe reproducer could easily trigger the issue.
* We booted a qemu virtual machine with a kernel containing both
patches with no issues.
[Where problems could occur]
* The likelihood of issues are low, specially due to the fact both patches
are very simple and they are on upstream kernel for more than 3 years (and were
quickly accepted in 4.14.y stable branch last week).
* With that sad, the second patch could potentially introduce issues
with super_block references - I honestly cannot conceive any issues
potentially caused by patch 1.
To manage notifications about this bug go to:
https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1934175/+subscriptions
--
Mailing list:
[Kernel-packages] [Bug 1934175] Re: Kernel oops due to uninitialized list on kernfs (kernfs_kill_sb)
This bug is awaiting verification that the kernel in -proposed solves
the problem. Please test the kernel and update this bug with the
results. If the problem is solved, change the tag 'verification-needed-
bionic' to 'verification-done-bionic'. If the problem still exists,
change the tag 'verification-needed-bionic' to 'verification-failed-
bionic'.
If verification is not done by 5 working days from today, this fix will
be dropped from the source code, and this bug will be closed.
See https://wiki.ubuntu.com/Testing/EnableProposed for documentation how
to enable and use -proposed. Thank you!
** Tags added: verification-needed-bionic
--
You received this bug notification because you are a member of Kernel
Packages, which is subscribed to linux in Ubuntu.
https://bugs.launchpad.net/bugs/1934175
Title:
Kernel oops due to uninitialized list on kernfs (kernfs_kill_sb)
Status in linux package in Ubuntu:
In Progress
Status in linux source package in Bionic:
Fix Committed
Bug description:
[Impact]
* We had a recent report of a kernel crash due to a NULL pointer dereference
in a Bionic 4.15 derivative kernel, as per the following log collected:
[...]
[537105.767348] SLUB: Unable to allocate memory on node -1,
gfp=0x14000c0(GFP_KERNEL)
[...]
[537105.767368] BUG: unable to handle kernel NULL pointer dereference at
0008
[537105.11] IP: kernfs_kill_sb+0x31/0x70
[537105.783582] PGD 0 P4D 0
[537105.787844] Oops: 0002 [#1] SMP PTI
[...]
RIP: 0010:kernfs_kill_sb+0x31/0x70
RSP: 0018:b90aec1afd00 EFLAGS: 00010286
RAX: RBX: 9fdbd567d900 RCX: a0143885ae01
RDX: RSI: a0143885ae00 RDI: a2937c40
RBP: b90aec1afd10 R08: a0150b581510 R09: 0001814d
R10: b90aec1afcd8 R11: 0100 R12: a01436e43000
R13: a01436e43000 R14: R15: 9fdbd567d900
FS: 7fe41a615b80() GS:a01afea4() knlGS:
CS: 0010 DS: ES: CR0: 80050033
CR2: 0008 CR3: 007dfe3cc003 CR4: 003606e0
DR0: DR1: DR2:
DR3: DR6: fffe0ff0 DR7: 0400
Call Trace:
sysfs_kill_sb+0x1f/0x40
deactivate_locked_super+0x48/0x80
kernfs_mount_ns+0x1eb/0x230
sysfs_mount+0x66/0xc0
mount_fs+0x37/0x160
? alloc_vfsmnt+0x1b3/0x230
vfs_kern_mount.part.24+0x5d/0x110
do_mount+0x5ed/0xce0
[...]
* The following detailed call stack plus the disassembly help to
understand the cause of the issue:
mount_fs()
--sysfs_mount()
kernfs_mount_ns()
--deactivate_locked_super()
sysfs_kill_sb()
--kernfs_kill_sb()
The below disassembly of kernfs_kill_sb() clarifies exactly the issue:
812f46e0 :
[ ... prologue ...]
48 8b 9f 08 04 00 00mov0x408(%rdi),%rbx # %rbx = kernfs_super_info
*info = sb->s_fs_info
49 89 fcmov%rdi,%r12 # %r12 = super_block *sb
48 c7 c7 40 7c 53 82mov$0x82537c40,%rdi # %rdi =
_mutex (global)
812f46f9: R_X86_64_32S kernfs_mutex
e8 ee da 67 00 callq 819721f0 #
mutex_lock(_mutex);
[...]
48 8b 53 18 mov0x18(%rbx),%rdx # %rdx = info->node
48 8b 43 20 mov0x20(%rbx),%rax # based on splat, RAX == 0x0
[info->head.prev]
48 89 42 08 mov%rax,0x8(%rdx) # <- OOPS [tried to assign
next->prev = prev, see __list_del()]
48 89 10mov%rdx,(%rax)
48 b8 00 01 00 00 00movabs $0xdead0100,%rax # node->next =
LIST_POISON1
[...]
* The fix for this issue comes from upstream commit 82382acec0c9
("kernfs: deal with kernfs_fill_super() failures"); this commit is a
very trivial fix that adds an INIT_LIST_HEAD(>node) in
kernfs_mount_ns(), making the list prev/next pointers valid since the
beginning. Unfortunately this commit wasn't CCed to stable email when
sent, so it wasn't automatically picked up by Ubuntu kernel; now it
was properly submitted to stable list [0].
* Along with this fix, we found another commit (7b745a4e4051) which is
a small/simple fix to correlated code, that also should have been sent
to 4.14.y stable branch, but for some reason wasn't. Since both
commits were accepted in linux-stable, we are hereby proposing the
backport for Ubuntu kernel 4.15.
[0]
https://lore.kernel.org/stable/20210622210622.9925-1-gpicc...@canonical.com/
[Test Case]
* We don't have a real test case, although low-memory condition or an
artificial kprobe reproducer could easily trigger the issue.
* We booted a qemu virtual machine with a kernel containing both
patches with no issues.
[Where problems could occur]
* The likelihood of issues are low, specially due to the fact both patches
are very simple and they are on upstream kernel for more than 3 years (and were
quickly
[Kernel-packages] [Bug 1934175] Re: Kernel oops due to uninitialized list on kernfs (kernfs_kill_sb)
** Changed in: linux (Ubuntu Bionic)
Status: In Progress => Fix Committed
--
You received this bug notification because you are a member of Kernel
Packages, which is subscribed to linux in Ubuntu.
https://bugs.launchpad.net/bugs/1934175
Title:
Kernel oops due to uninitialized list on kernfs (kernfs_kill_sb)
Status in linux package in Ubuntu:
In Progress
Status in linux source package in Bionic:
Fix Committed
Bug description:
[Impact]
* We had a recent report of a kernel crash due to a NULL pointer dereference
in a Bionic 4.15 derivative kernel, as per the following log collected:
[...]
[537105.767348] SLUB: Unable to allocate memory on node -1,
gfp=0x14000c0(GFP_KERNEL)
[...]
[537105.767368] BUG: unable to handle kernel NULL pointer dereference at
0008
[537105.11] IP: kernfs_kill_sb+0x31/0x70
[537105.783582] PGD 0 P4D 0
[537105.787844] Oops: 0002 [#1] SMP PTI
[...]
RIP: 0010:kernfs_kill_sb+0x31/0x70
RSP: 0018:b90aec1afd00 EFLAGS: 00010286
RAX: RBX: 9fdbd567d900 RCX: a0143885ae01
RDX: RSI: a0143885ae00 RDI: a2937c40
RBP: b90aec1afd10 R08: a0150b581510 R09: 0001814d
R10: b90aec1afcd8 R11: 0100 R12: a01436e43000
R13: a01436e43000 R14: R15: 9fdbd567d900
FS: 7fe41a615b80() GS:a01afea4() knlGS:
CS: 0010 DS: ES: CR0: 80050033
CR2: 0008 CR3: 007dfe3cc003 CR4: 003606e0
DR0: DR1: DR2:
DR3: DR6: fffe0ff0 DR7: 0400
Call Trace:
sysfs_kill_sb+0x1f/0x40
deactivate_locked_super+0x48/0x80
kernfs_mount_ns+0x1eb/0x230
sysfs_mount+0x66/0xc0
mount_fs+0x37/0x160
? alloc_vfsmnt+0x1b3/0x230
vfs_kern_mount.part.24+0x5d/0x110
do_mount+0x5ed/0xce0
[...]
* The following detailed call stack plus the disassembly help to
understand the cause of the issue:
mount_fs()
--sysfs_mount()
kernfs_mount_ns()
--deactivate_locked_super()
sysfs_kill_sb()
--kernfs_kill_sb()
The below disassembly of kernfs_kill_sb() clarifies exactly the issue:
812f46e0 :
[ ... prologue ...]
48 8b 9f 08 04 00 00mov0x408(%rdi),%rbx # %rbx = kernfs_super_info
*info = sb->s_fs_info
49 89 fcmov%rdi,%r12 # %r12 = super_block *sb
48 c7 c7 40 7c 53 82mov$0x82537c40,%rdi # %rdi =
_mutex (global)
812f46f9: R_X86_64_32S kernfs_mutex
e8 ee da 67 00 callq 819721f0 #
mutex_lock(_mutex);
[...]
48 8b 53 18 mov0x18(%rbx),%rdx # %rdx = info->node
48 8b 43 20 mov0x20(%rbx),%rax # based on splat, RAX == 0x0
[info->head.prev]
48 89 42 08 mov%rax,0x8(%rdx) # <- OOPS [tried to assign
next->prev = prev, see __list_del()]
48 89 10mov%rdx,(%rax)
48 b8 00 01 00 00 00movabs $0xdead0100,%rax # node->next =
LIST_POISON1
[...]
* The fix for this issue comes from upstream commit 82382acec0c9
("kernfs: deal with kernfs_fill_super() failures"); this commit is a
very trivial fix that adds an INIT_LIST_HEAD(>node) in
kernfs_mount_ns(), making the list prev/next pointers valid since the
beginning. Unfortunately this commit wasn't CCed to stable email when
sent, so it wasn't automatically picked up by Ubuntu kernel; now it
was properly submitted to stable list [0].
* Along with this fix, we found another commit (7b745a4e4051) which is
a small/simple fix to correlated code, that also should have been sent
to 4.14.y stable branch, but for some reason wasn't. Since both
commits were accepted in linux-stable, we are hereby proposing the
backport for Ubuntu kernel 4.15.
[0]
https://lore.kernel.org/stable/20210622210622.9925-1-gpicc...@canonical.com/
[Test Case]
* We don't have a real test case, although low-memory condition or an
artificial kprobe reproducer could easily trigger the issue.
* We booted a qemu virtual machine with a kernel containing both
patches with no issues.
[Where problems could occur]
* The likelihood of issues are low, specially due to the fact both patches
are very simple and they are on upstream kernel for more than 3 years (and were
quickly accepted in 4.14.y stable branch last week).
* With that sad, the second patch could potentially introduce issues
with super_block references - I honestly cannot conceive any issues
potentially caused by patch 1.
To manage notifications about this bug go to:
https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1934175/+subscriptions
--
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[Kernel-packages] [Bug 1934175] Re: Kernel oops due to uninitialized list on kernfs (kernfs_kill_sb)
** Description changed:
- TBD
+ [Impact]
+ * We had a recent report of a kernel crash due to a NULL pointer dereference
in a Bionic 4.15 derivative kernel, as per the following log collected:
+
+ [...]
+ [537105.767348] SLUB: Unable to allocate memory on node -1,
gfp=0x14000c0(GFP_KERNEL)
+ [...]
+ [537105.767368] BUG: unable to handle kernel NULL pointer dereference at
0008
+ [537105.11] IP: kernfs_kill_sb+0x31/0x70
+ [537105.783582] PGD 0 P4D 0
+ [537105.787844] Oops: 0002 [#1] SMP PTI
+ [...]
+ RIP: 0010:kernfs_kill_sb+0x31/0x70
+ RSP: 0018:b90aec1afd00 EFLAGS: 00010286
+ RAX: RBX: 9fdbd567d900 RCX: a0143885ae01
+ RDX: RSI: a0143885ae00 RDI: a2937c40
+ RBP: b90aec1afd10 R08: a0150b581510 R09: 0001814d
+ R10: b90aec1afcd8 R11: 0100 R12: a01436e43000
+ R13: a01436e43000 R14: R15: 9fdbd567d900
+ FS: 7fe41a615b80() GS:a01afea4() knlGS:
+ CS: 0010 DS: ES: CR0: 80050033
+ CR2: 0008 CR3: 007dfe3cc003 CR4: 003606e0
+ DR0: DR1: DR2:
+ DR3: DR6: fffe0ff0 DR7: 0400
+ Call Trace:
+ sysfs_kill_sb+0x1f/0x40
+ deactivate_locked_super+0x48/0x80
+ kernfs_mount_ns+0x1eb/0x230
+ sysfs_mount+0x66/0xc0
+ mount_fs+0x37/0x160
+ ? alloc_vfsmnt+0x1b3/0x230
+ vfs_kern_mount.part.24+0x5d/0x110
+ do_mount+0x5ed/0xce0
+ [...]
+
+ * The following detailed call stack plus the disassembly help to
+ understand the cause of the issue:
+
+ mount_fs()
+ --sysfs_mount()
+ kernfs_mount_ns()
+ --deactivate_locked_super()
+ sysfs_kill_sb()
+ --kernfs_kill_sb()
+
+ The below disassembly of kernfs_kill_sb() clarifies exactly the issue:
+
+ 812f46e0 :
+ [ ... prologue ...]
+ 48 8b 9f 08 04 00 00mov0x408(%rdi),%rbx # %rbx = kernfs_super_info
*info = sb->s_fs_info
+ 49 89 fcmov%rdi,%r12 # %r12 = super_block *sb
+ 48 c7 c7 40 7c 53 82mov$0x82537c40,%rdi # %rdi =
_mutex (global)
+ 812f46f9: R_X86_64_32S kernfs_mutex
+ e8 ee da 67 00 callq 819721f0 #
mutex_lock(_mutex);
+ [...]
+ 48 8b 53 18 mov0x18(%rbx),%rdx # %rdx = info->node
+ 48 8b 43 20 mov0x20(%rbx),%rax # based on splat, RAX == 0x0
[info->head.prev]
+ 48 89 42 08 mov%rax,0x8(%rdx) # <- OOPS [tried to assign
next->prev = prev, see __list_del()]
+ 48 89 10mov%rdx,(%rax)
+ 48 b8 00 01 00 00 00movabs $0xdead0100,%rax # node->next =
LIST_POISON1
+ [...]
+
+ * The fix for this issue comes from upstream commit 82382acec0c9
+ ("kernfs: deal with kernfs_fill_super() failures"); this commit is a
+ very trivial fix that adds an INIT_LIST_HEAD(>node) in
+ kernfs_mount_ns(), making the list prev/next pointers valid since the
+ beginning. Unfortunately this commit wasn't CCed to stable email when
+ sent, so it wasn't automatically picked up by Ubuntu kernel; now it was
+ properly submitted to stable list [0].
+
+ * Along with this fix, we found another commit (7b745a4e4051) which is a
+ small/simple fix to correlated code, that also should have been sent to
+ 4.14.y stable branch, but for some reason wasn't. Since both commits
+ were accepted in linux-stable, we are hereby proposing the backport for
+ Ubuntu kernel 4.15.
+
+ [0]
+ https://lore.kernel.org/stable/20210622210622.9925-1-gpicc...@canonical.com/
+
+
+ [Test Case]
+ * We don't have a real test case, although low-memory condition or an
artificial kprobe reproducer could easily trigger the issue.
+
+ * We booted a qemu virtual machine with a kernel containing both patches
+ with no issues.
+
+
+ [Where problems could occur]
+ * The likelihood of issues are low, specially due to the fact both patches
are very simple and they are on upstream kernel for more than 3 years (and were
quickly accepted in 4.14.y stable branch last week).
+
+ * With that sad, the second patch could potentially introduce issues
+ with super_block references - I honestly cannot conceive any issues
+ potentially caused by patch 1.
--
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https://bugs.launchpad.net/bugs/1934175
Title:
Kernel oops due to uninitialized list on kernfs (kernfs_kill_sb)
Status in linux package in Ubuntu:
In Progress
Status in linux source package in Bionic:
In Progress
Bug description:
[Impact]
* We had a recent report of a kernel crash due to a NULL pointer dereference
in a Bionic 4.15 derivative kernel, as per the following log collected:
[...]
[537105.767348] SLUB: Unable to allocate memory on node -1,
gfp=0x14000c0(GFP_KERNEL)
[...]
[537105.767368] BUG: unable to handle kernel NULL pointer dereference at
0008
[537105.11]
