The commit is pushed to "branch-rh10-6.12.0-55.13.1.2.x.vz10-ovz" and will
appear at [email protected]:openvz/vzkernel.git
after rh10-6.12.0-55.13.1.2.9.vz10
------>
commit b9cc0a24cc4c8a67951d79d62cd4bfb520805c04
Author: Vasileios Almpanis <[email protected]>
Date: Thu Oct 9 14:47:57 2025 +0000
dm-ploop: null pointer dereference in ploop_put_delta()
The ploop_add_delta() function calls file_clone_open() to create multiple
file handles, but only checks for NULL return values. However,
file_clone_open() can return ERR_PTR() on failure, which gets stored as
a corrupted file pointer in deltas[level].mtfile[i].
Later, during cleanup in ploop_put_delta(), fput() is called on these
corrupted pointers, causing the kernel to attempt accessing invalid
memory addresses resulting in NULL pointer dereference crashes.
BUG: kernel NULL pointer dereference, address: 0000000000000034
#PF: supervisor write access in kernel mode
#PF: error_code(0x0002) - not-present page
PGD 0 P4D 0
Oops: 0002 [#1] PREEMPT SMP PTI
CPU: 6 PID: 274635 Comm: dmsetup ve: / Kdump: loaded Tainted: G
X ------- --- 5.14.0-427.77.1.vz9.86.12 #1 86.12
Hardware name: Supermicro SYS-5039MS-H12NR/X11SSE-F, BIOS 2.3 12/12/2019
RIP: 0010:fput_many+0x7/0x90
RSP: 0018:ffffa55e45ab3bd0 EFLAGS: 00010286
RAX: 0000000000000000 RBX: 0000000000000000 RCX: 0000000000000000
RDX: 0000000000000001 RSI: 0000000000000001 RDI: fffffffffffffffc
RBP: ffff8aaf304a2800 R08: ffff8aaebbc83800 R09: 20c49ba5e353f7cf
R10: ffff8aaec85428f0 R11: ffffffffc05c41fc R12: ffff8aaf287d9f40
R13: ffff8aaf28692000 R14: 0000000000000004 R15: 0000000000000003
FS: 00007feb47a0d840(0000) GS:ffff8abc77b80000(0000)
knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000000000000034 CR3: 0000000323e94003 CR4: 00000000003706e0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
<TASK>
? show_trace_log_lvl+0x1c4/0x2df
? show_trace_log_lvl+0x1c4/0x2df
? ploop_put_delta+0x51/0x76 [ploop]
? __die_body.cold+0x8/0xd
? page_fault_oops+0x134/0x170
? exc_page_fault+0x62/0x150
? asm_exc_page_fault+0x22/0x30
? fuse_generic_request_alloc+0x1c/0x80 [fuse]
? fput_many+0x7/0x90
ploop_put_delta+0x51/0x76 [ploop]
ploop_destroy+0x17b/0x2a0 [ploop]
dm_table_destroy+0x59/0x120 [dm_mod]
dev_remove+0xdb/0x1a0 [dm_mod]
ctl_ioctl+0x1a5/0x290 [dm_mod]
dm_ctl_ioctl+0xa/0x20 [dm_mod]
__x64_sys_ioctl+0x87/0xc0
do_syscall_64+0x59/0x90
? syscall_exit_work+0x103/0x130
? syscall_exit_to_user_mode+0x19/0x40
? do_syscall_64+0x69/0x90
? exit_to_user_mode_loop+0xd0/0x130
? exit_to_user_mode_prepare+0xb6/0x100
? syscall_exit_to_user_mode+0x19/0x40
? do_syscall_64+0x69/0x90
? do_user_addr_fault+0x1d6/0x6a0
? syscall_exit_work+0x103/0x130
? exc_page_fault+0x62/0x150
entry_SYSCALL_64_after_hwframe+0x77/0xe1
RIP: 0033:0x7feb4783ec6b
RSP: 002b:00007ffdc8dc7c98 EFLAGS: 00000206 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 00007feb47c0fbd0 RCX: 00007feb4783ec6b
RDX: 00005651f9b00c80 RSI: 00000000c138fd04 RDI: 0000000000000003
RBP: 00007feb47c4c316 R08: 00007feb47c4f2d8 R09: 00007ffdc8dc7af0
R10: 00007feb47c4c316 R11: 0000000000000206 R12: 00005651f9b00c80
R13: 00005651f9b00d30 R14: 00007feb47c4c316 R15: 00005651f9b00a00
</TASK>
CR2: 0000000000000034
Fix it by using IS_ERR() to properly detect error pointers from
file_clone_open()
https://virtuozzo.atlassian.net/browse/VSTOR-116965
Signed-off-by: Vasileios Almpanis <[email protected]>
Feature: dm-ploop: ploop target driver
---
drivers/md/dm-ploop-bat.c | 8 +++++---
1 file changed, 5 insertions(+), 3 deletions(-)
diff --git a/drivers/md/dm-ploop-bat.c b/drivers/md/dm-ploop-bat.c
index fbf949f4dd0fb..7746babf04a77 100644
--- a/drivers/md/dm-ploop-bat.c
+++ b/drivers/md/dm-ploop-bat.c
@@ -480,6 +480,7 @@ int ploop_add_delta(struct ploop *ploop, u32 level, struct
file *file, bool is_r
{
struct ploop_delta *deltas = ploop->deltas;
struct rb_root md_root = RB_ROOT;
+ struct file *cloned_file = NULL;
loff_t file_size;
u32 nr_be;
int ret, i;
@@ -510,11 +511,12 @@ int ploop_add_delta(struct ploop *ploop, u32 level,
struct file *file, bool is_r
goto out;
}
for (i = 0; i < ploop->nkt_runners; i++) {
- deltas[level].mtfile[i] = file_clone_open(file);
- if (!deltas[level].mtfile[i]) {
- ret = ENOMEM;
+ cloned_file = file_clone_open(file);
+ if (IS_ERR(cloned_file)) {
+ ret = PTR_ERR(cloned_file);
goto out;
}
+ deltas[level].mtfile[i] = cloned_file;
}
deltas[level].file_size = file_size;
deltas[level].file_preallocated_area_start = file_size;
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