Re: BUG: unable to handle kernel NULL pointer dereference in generic_perform_write (2)

2020-06-10 Thread syzbot 
Hello,

syzbot has tested the proposed patch and the reproducer did not trigger crash:

Reported-and-tested-by: syzbot+bca9799bf12925619...@syzkaller.appspotmail.com

Tested on:

commit: 5749fe5a ext4: avoid race conditions when remounting with ..
git tree:   https://git.kernel.org/pub/scm/linux/kernel/git/tytso/ext4.git
kernel config:  https://syzkaller.appspot.com/x/.config?x=175fcaead7a60c3f
dashboard link: https://syzkaller.appspot.com/bug?extid=bca9799bf129256190da
compiler:   gcc (GCC) 9.0.0 20181231 (experimental)

Note: testing is done by a robot and is best-effort only.

Re: BUG: unable to handle kernel NULL pointer dereference in generic_perform_write (2)

2020-06-10 Thread Theodore Y. Ts'o 
#syz test: https://git.kernel.org/pub/scm/linux/kernel/git/tytso/ext4.git 
5749fe5af3db176659978718ddaecebb450cdb6b

Re: BUG: unable to handle kernel NULL pointer dereference in generic_perform_write (2)

2020-06-10 Thread syzbot 
Hello,

syzbot has tested the proposed patch but the reproducer still triggered crash:
BUG: unable to handle kernel NULL pointer dereference in generic_perform_write

BUG: kernel NULL pointer dereference, address: 
#PF: supervisor instruction fetch in kernel mode
#PF: error_code(0x0010) - not-present page
PGD a3819067 P4D a3819067 PUD a2ea0067 PMD 0 
Oops: 0010 [#1] PREEMPT SMP KASAN
CPU: 1 PID: 9214 Comm: syz-executor.1 Not tainted 5.6.0-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 
01/01/2011
RIP: 0010:0x0
Code: Bad RIP value.
RSP: 0018:c90006d1fa38 EFLAGS: 00010246
RAX: 883cb0a0 RBX:  RCX: 0001
RDX:  RSI: 888082b89a60 RDI: 88808a414a80
RBP: 888082b89a60 R08:  R09: c90006d1fac0
R10: 888072cd6607 R11: ed100e59acc0 R12: 0001
R13:  R14:  R15: c90006d1fd18
FS:  7f310f3f3700() GS:8880ae70() knlGS:
CS:  0010 DS:  ES:  CR0: 80050033
CR2: ffd6 CR3: 904f1000 CR4: 001406e0
DR0:  DR1:  DR2: 
DR3:  DR6: fffe0ff0 DR7: 0400
Call Trace:
 generic_perform_write+0x20a/0x4e0 mm/filemap.c:3302
 ext4_buffered_write_iter+0x1f7/0x450 fs/ext4/file.c:270
 ext4_file_write_iter+0x1ec/0x13f0 fs/ext4/file.c:642
 call_write_iter include/linux/fs.h:1907 [inline]
 new_sync_write+0x4a2/0x700 fs/read_write.c:484
 __vfs_write+0xc9/0x100 fs/read_write.c:497
 vfs_write+0x268/0x5d0 fs/read_write.c:559
 ksys_write+0x12d/0x250 fs/read_write.c:612
 do_syscall_64+0xf6/0x7d0 arch/x86/entry/common.c:295
 entry_SYSCALL_64_after_hwframe+0x49/0xb3
RIP: 0033:0x45c889
Code: ad b6 fb ff c3 66 2e 0f 1f 84 00 00 00 00 00 66 90 48 89 f8 48 89 f7 48 
89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 0f 83 
7b b6 fb ff c3 66 2e 0f 1f 84 00 00 00 00
RSP: 002b:7f310f3f2c78 EFLAGS: 0246 ORIG_RAX: 0001
RAX: ffda RBX: 7f310f3f36d4 RCX: 0045c889
RDX: 0001 RSI: 2080 RDI: 0003
RBP: 0076bfa0 R08:  R09: 
R10:  R11: 0246 R12: 
R13: 0cdc R14: 004cf042 R15: 0076bfac
Modules linked in:
CR2: 
---[ end trace ff42a65b331528ba ]---
RIP: 0010:0x0
Code: Bad RIP value.
RSP: 0018:c90006d1fa38 EFLAGS: 00010246
RAX: 883cb0a0 RBX:  RCX: 0001
RDX:  RSI: 888082b89a60 RDI: 88808a414a80
RBP: 888082b89a60 R08:  R09: c90006d1fac0
R10: 888072cd6607 R11: ed100e59acc0 R12: 0001
R13:  R14:  R15: c90006d1fd18
FS:  7f310f3f3700() GS:8880ae70() knlGS:
CS:  0010 DS:  ES:  CR0: 80050033
CR2: 0076c061 CR3: 904f1000 CR4: 001406e0
DR0:  DR1:  DR2: 
DR3:  DR6: fffe0ff0 DR7: 0400


Tested on:

commit: 5b8b9d0c Merge branch 'akpm' (patches from Andrew)
git tree:   https://git.kernel.org/pub/scm/linux/kernel/git/tytso/ext4.git
console output: https://syzkaller.appspot.com/x/log.txt?x=158b23ca10
kernel config:  https://syzkaller.appspot.com/x/.config?x=23c5a352e32a1944
dashboard link: https://syzkaller.appspot.com/bug?extid=bca9799bf129256190da
compiler:   gcc (GCC) 9.0.0 20181231 (experimental)

Re: BUG: unable to handle kernel NULL pointer dereference in generic_perform_write (2)

2020-06-10 Thread Theodore Y. Ts'o 
#syz test: https://git.kernel.org/pub/scm/linux/kernel/git/tytso/ext4.git 
5b8b9d0c6d0e0f1993c6c56deaf9646942c49d94

Re: BUG: unable to handle kernel NULL pointer dereference in generic_perform_write (2)

2020-06-10 Thread syzbot 
Hello,

syzbot tried to test the proposed patch but build/boot failed:

syzkaller build failed: failed to run ["make" "target"]: exit status 2
GOOS=linux GOARCH=amd64 go install ./syz-fuzzer
# github.com/google/syzkaller/sys/netbsd/gen
sys/netbsd/gen/amd64.go:41:58: undefined: Field
sys/netbsd/gen/amd64.go:44:10: undefined: Ref
sys/netbsd/gen/amd64.go:45:59: undefined: Ref
sys/netbsd/gen/amd64.go:46:70: undefined: Field
sys/netbsd/gen/amd64.go:49:66: undefined: Field
sys/netbsd/gen/amd64.go:54:60: undefined: Field
sys/netbsd/gen/amd64.go:58:66: undefined: Field
sys/netbsd/gen/amd64.go:62:68: undefined: Field
sys/netbsd/gen/amd64.go:68:62: undefined: Field
sys/netbsd/gen/amd64.go:72:59: undefined: Ref
sys/netbsd/gen/amd64.go:72:59: too many errors
# github.com/google/syzkaller/sys/akaros/gen
sys/akaros/gen/amd64.go:23:63: undefined: Field
sys/akaros/gen/amd64.go:26:69: undefined: Field
sys/akaros/gen/amd64.go:29:56: undefined: Field
sys/akaros/gen/amd64.go:34:52: undefined: Field
sys/akaros/gen/amd64.go:39:67: undefined: Field
sys/akaros/gen/amd64.go:43:54: undefined: Field
sys/akaros/gen/amd64.go:48:54: undefined: Field
sys/akaros/gen/amd64.go:51:64: undefined: Field
sys/akaros/gen/amd64.go:56:51: undefined: Field
sys/akaros/gen/amd64.go:62:56: undefined: Field
sys/akaros/gen/amd64.go:62:56: too many errors
# github.com/google/syzkaller/sys/openbsd/gen
sys/openbsd/gen/amd64.go:49:55: undefined: Field
sys/openbsd/gen/amd64.go:53:10: undefined: Ref
sys/openbsd/gen/amd64.go:54:60: undefined: Field
sys/openbsd/gen/amd64.go:58:10: undefined: Ref
sys/openbsd/gen/amd64.go:59:61: undefined: Field
sys/openbsd/gen/amd64.go:63:10: undefined: Ref
sys/openbsd/gen/amd64.go:64:60: undefined: Field
sys/openbsd/gen/amd64.go:68:10: undefined: Ref
sys/openbsd/gen/amd64.go:69:51: undefined: Field
sys/openbsd/gen/amd64.go:72:52: undefined: Field
sys/openbsd/gen/amd64.go:72:52: too many errors
# github.com/google/syzkaller/sys/test/gen
sys/test/gen/32_fork_shmem.go:29:55: unknown field 'Attrs' in struct literal of 
type prog.Syscall
sys/test/gen/32_fork_shmem.go:30:45: unknown field 'Attrs' in struct literal of 
type prog.Syscall
sys/test/gen/32_fork_shmem.go:31:50: undefined: Ref
sys/test/gen/32_fork_shmem.go:31:60: unknown field 'Attrs' in struct literal of 
type prog.Syscall
sys/test/gen/32_fork_shmem.go:32:53: undefined: Field
sys/test/gen/32_fork_shmem.go:34:5: unknown field 'Attrs' in struct literal of 
type prog.Syscall
sys/test/gen/32_fork_shmem.go:35:66: undefined: Ref
sys/test/gen/32_fork_shmem.go:36:53: undefined: Field
sys/test/gen/32_fork_shmem.go:39:62: undefined: Field
sys/test/gen/32_fork_shmem.go:42:48: undefined: Field
sys/test/gen/32_fork_shmem.go:42:48: too many errors
# github.com/google/syzkaller/sys/freebsd/gen
sys/freebsd/gen/386.go:49:76: undefined: Field
sys/freebsd/gen/386.go:54:60: undefined: Field
sys/freebsd/gen/386.go:58:68: undefined: Field
sys/freebsd/gen/386.go:65:67: undefined: Field
sys/freebsd/gen/386.go:71:68: undefined: Field
sys/freebsd/gen/386.go:77:67: undefined: Field
sys/freebsd/gen/386.go:83:67: undefined: Field
sys/freebsd/gen/386.go:89:68: undefined: Field
sys/freebsd/gen/386.go:95:69: undefined: Field
sys/freebsd/gen/386.go:101:85: undefined: Field
sys/freebsd/gen/386.go:101:85: too many errors
# github.com/google/syzkaller/sys/windows/gen
sys/windows/gen/amd64.go:23:51: undefined: Field
sys/windows/gen/amd64.go:26:53: undefined: Field
sys/windows/gen/amd64.go:29:59: undefined: Field
sys/windows/gen/amd64.go:32:75: undefined: Field
sys/windows/gen/amd64.go:35:51: undefined: Field
sys/windows/gen/amd64.go:45:57: undefined: Field
sys/windows/gen/amd64.go:55:85: undefined: Field
sys/windows/gen/amd64.go:66:69: undefined: Field
sys/windows/gen/amd64.go:77:97: undefined: Field
sys/windows/gen/amd64.go:88:89: undefined: Field
sys/windows/gen/amd64.go:88:89: too many errors
# github.com/google/syzkaller/sys/fuchsia/gen
sys/fuchsia/gen/amd64.go:96:45: undefined: Field
sys/fuchsia/gen/amd64.go:99:45: undefined: Field
sys/fuchsia/gen/amd64.go:103:45: undefined: Field
sys/fuchsia/gen/amd64.go:108:45: undefined: Field
sys/fuchsia/gen/amd64.go:111:45: undefined: Field
sys/fuchsia/gen/amd64.go:114:10: undefined: Ref
sys/fuchsia/gen/amd64.go:115:41: undefined: Field
sys/fuchsia/gen/amd64.go:117:10: undefined: Ref
sys/fuchsia/gen/amd64.go:118:43: undefined: Field
sys/fuchsia/gen/amd64.go:121:10: undefined: Ref
sys/fuchsia/gen/amd64.go:121:10: too many errors
# github.com/google/syzkaller/sys/linux/gen
sys/linux/gen/386.go:296:58: undefined: Field
sys/linux/gen/386.go:301:10: undefined: Ref
sys/linux/gen/386.go:302:62: undefined: Field
sys/linux/gen/386.go:307:10: undefined: Ref
sys/linux/gen/386.go:308:63: undefined: Field
sys/linux/gen/386.go:313:10: undefined: Ref
sys/linux/gen/386.go:314:67: undefined: Field
sys/linux/gen/386.go:319:10: undefined: Ref
sys/linux/gen/386.go:320:63: undefined: Field
sys/linux/gen/386.go:325:10: undefined: Ref
sys/linux/gen/386.go:325:10: too many errors

Re: BUG: unable to handle kernel NULL pointer dereference in generic_perform_write (2)

2020-06-10 Thread Theodore Y. Ts'o 
#syz test: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git 
5b8b9d0c6d0e0f1993c6c56deaf9646942c49d94