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New: NULL pointer dereference

Bug 209719 Andrew Morton 3 participants 4 messages Oct 16, 2020 – Oct 18, 2020 1 message not in the archive

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Andrew Morton

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(switched to email. Please respond via emailed reply-to-all, not via the bugzilla web interface).

Quoted 25 lines · On Fri, 16 Oct 2020 14:59:08 +0000 [email protected] wrote:

https://bugzilla.kernel.org/show_bug.cgi?id=209719

Bug ID: 209719
Summary: NULL pointer dereference
Product: Memory Management
Version: 2.5
Kernel Version: 5.9-next
Hardware: All
OS: Linux
Tree: Mainline
Status: NEW
Severity: blocking
Priority: P1
Component: Other
Assignee: [email protected]
Reporter: [email protected]
Regression: No

Created attachment 293041
--> https://bugzilla.kernel.org/attachment.cgi?id=293041&action=edit
Kernel oops from journalctl

Im sorry i didnt know to which table i should report this bug. So if i reported it to incorrect product and component then im sorry.

Quoted 7 lines

System: Acer Nitro 5 AN515-42
Kernel: 5.9-next-20201015

I updated to newest tag on linux-next and system crashed at boot. Previously it only showed systemD message and then hidden it which i suspect is AMDGPU bug. I guess this bug is happening even before that one or the AMDGPU bug was fixed in linux-next.

Thanks for the report.

Probably autofs is interacting poorly with the __kernel_write() changes in Christoph's 4d03e3cc59828 ("fs: don't allow kernel reads and writes without iter ops"). I pasted the relevant oops trace. Could folks please take a look?

Oct 16 16:38:53 TimeMachine kernel: BUG: kernel NULL pointer dereference, address: 0000000000000000
Oct 16 16:38:53 TimeMachine kernel: #PF: supervisor read access in kernel mode
Oct 16 16:38:53 TimeMachine kernel: #PF: error_code(0x0000) - not-present page
Oct 16 16:38:53 TimeMachine kernel: PGD 0 P4D 0 
Oct 16 16:38:53 TimeMachine kernel: Oops: 0000 [#1] PREEMPT SMP NOPTI
Oct 16 16:38:53 TimeMachine kernel: CPU: 1 PID: 319 Comm: systemd-binfmt Not tainted 5.9.0-next-20201015-1-next-git #1
Oct 16 16:38:53 TimeMachine kernel: Hardware name: Acer Nitro AN515-42/Freed_RRS, BIOS V1.13 02/11/2019
Oct 16 16:38:53 TimeMachine kernel: RIP: 0010:__kernel_write+0x11b/0x2c0
Oct 16 16:38:53 TimeMachine kernel: Code: 8b 54 24 20 0f b6 92 8f 00 00 00 65 48 8b 0c 25 c0 7b 01 00 48 8b b1 48 08 00 00 31 c9 48 85 f6 74 04 0f b7 4e 14 89 44 24 58 <48> 8b 03 be 01 00 00 00 48 8d 7c 24 10 66 89 54 24 5c 48 89 e2 66
Oct 16 16:38:53 TimeMachine kernel: RSP: 0018:ffff9c04c0e6f880 EFLAGS: 00010286
Oct 16 16:38:53 TimeMachine kernel: RAX: 0000000000020000 RBX: 0000000000000000 RCX: 0000000000000000
Oct 16 16:38:53 TimeMachine kernel: RDX: 0000000000000000 RSI: ffff928701167a28 RDI: ffff9c04c0e6f8e8
Oct 16 16:38:53 TimeMachine kernel: RBP: ffff9287046a7d00 R08: 0000000000000130 R09: 00000010af978cf7
Oct 16 16:38:53 TimeMachine kernel: R10: 000000000000000f R11: ffff928708ce9110 R12: ffff9287046a7d00
Oct 16 16:38:53 TimeMachine kernel: R13: ffff9c04c0e6f8b8 R14: ffff928709f6d868 R15: 0000000000000130
Oct 16 16:38:53 TimeMachine kernel: FS:  00007fb657195000(0000) GS:ffff928a3fc40000(0000) knlGS:0000000000000000
Oct 16 16:38:53 TimeMachine kernel: CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
Oct 16 16:38:53 TimeMachine kernel: CR2: 0000000000000000 CR3: 0000000102f8e000 CR4: 00000000003506e0
Oct 16 16:38:53 TimeMachine kernel: Call Trace:
Oct 16 16:38:53 TimeMachine kernel:  autofs_notify_daemon+0x13f/0x2b0
Oct 16 16:38:53 TimeMachine kernel:  ? cpumask_next_and+0x19/0x20
Oct 16 16:38:53 TimeMachine kernel:  autofs_wait+0x606/0x7e0
Oct 16 16:38:53 TimeMachine kernel:  ? chacha_block_generic+0x6f/0xb0
Oct 16 16:38:53 TimeMachine kernel:  ? autofs_mount_wait+0x49/0xf0
Oct 16 16:38:53 TimeMachine kernel:  ? _raw_spin_unlock+0x16/0x30
Oct 16 16:38:53 TimeMachine kernel:  autofs_mount_wait+0x49/0xf0
Oct 16 16:38:53 TimeMachine kernel:  autofs_d_automount+0xd9/0x1f0
Oct 16 16:38:53 TimeMachine kernel:  __traverse_mounts+0x8f/0x220
Oct 16 16:38:53 TimeMachine kernel:  step_into+0x3d6/0x700
Oct 16 16:38:53 TimeMachine kernel:  walk_component+0x83/0x1b0
Oct 16 16:38:53 TimeMachine kernel:  ? _raw_spin_unlock+0x16/0x30
Oct 16 16:38:53 TimeMachine kernel:  link_path_walk+0x25d/0x390
Oct 16 16:38:53 TimeMachine kernel:  path_openat+0x8d/0x10b0
Oct 16 16:38:53 TimeMachine kernel:  ? _raw_read_unlock+0x18/0x30
Oct 16 16:38:53 TimeMachine kernel:  ? kmem_cache_free+0x116/0x450
Oct 16 16:38:53 TimeMachine kernel:  do_filp_open+0x9c/0x140
Oct 16 16:38:53 TimeMachine kernel:  do_sys_openat2+0xb1/0x160
Oct 16 16:38:53 TimeMachine kernel:  __x64_sys_openat+0x54/0x90
Oct 16 16:38:53 TimeMachine kernel:  do_syscall_64+0x33/0x40
Oct 16 16:38:53 TimeMachine kernel:  entry_SYSCALL_64_after_hwframe+0x44/0xa9
Oct 16 16:38:53 TimeMachine kernel: RIP: 0033:0x7fb657f85c1b
#2 lore raw
Quoted 2 lines

(switched to email. Please respond via emailed reply-to-all, not via the bugzilla web interface).

OK will do when this bug gets some traction.
Thank you.