* Eiichi Tsukata <de...@etsukata.com> [2019-06-14 16:40:25]:
> Just like the case of commit 8b05a3a7503c ("tracing/kprobes: Fix NULL
> pointer dereference in trace_kprobe_create()"), writing an incorrectly
> formatted string to uprobe_events can trigger NULL pointer dereference.
>
> Reporeducer:
>
> # echo r > /sys/kernel/debug/tracing/uprobe_events
>
> dmesg:
>
> BUG: kernel NULL pointer dereference, address: 0000000000000000
> #PF: supervisor read access in kernel mode
> #PF: error_code(0x0000) - not-present page
> PGD 8000000079d12067 P4D 8000000079d12067 PUD 7b7ab067 PMD 0
> Oops: 0000 [#1] PREEMPT SMP PTI
> CPU: 0 PID: 1903 Comm: bash Not tainted 5.2.0-rc3+ #15
> Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.12.0-2.fc30
> 04/01/2014
> RIP: 0010:strchr+0x0/0x30
> Code: c0 eb 0d 84 c9 74 18 48 83 c0 01 48 39 d0 74 0f 0f b6 0c 07 3a 0c 06
> 74 ea 19 c0 83 c8 01 c3 31 c0 c3 0f 1f 84 00 00 00 00 00 <0f> b6 07 89 f2 40
> 38 f0 75 0e eb 13 0f b6 47 01 48 83 c
> RSP: 0018:ffffb55fc0403d10 EFLAGS: 00010293
>
> RAX: ffff993ffb793400 RBX: 0000000000000000 RCX: ffffffffa4852625
> RDX: 0000000000000000 RSI: 000000000000002f RDI: 0000000000000000
> RBP: ffffb55fc0403dd0 R08: ffff993ffb793400 R09: 0000000000000000
> R10: 0000000000000000 R11: 0000000000000000 R12: 0000000000000000
> R13: ffff993ff9cc1668 R14: 0000000000000001 R15: 0000000000000000
> FS: 00007f30c5147700(0000) GS:ffff993ffda00000(0000) knlGS:0000000000000000
> CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
> CR2: 0000000000000000 CR3: 000000007b628000 CR4: 00000000000006f0
> Call Trace:
> trace_uprobe_create+0xe6/0xb10
> ? __kmalloc_track_caller+0xe6/0x1c0
> ? __kmalloc+0xf0/0x1d0
> ? trace_uprobe_create+0xb10/0xb10
> create_or_delete_trace_uprobe+0x35/0x90
> ? trace_uprobe_create+0xb10/0xb10
> trace_run_command+0x9c/0xb0
> trace_parse_run_command+0xf9/0x1eb
> ? probes_open+0x80/0x80
> __vfs_write+0x43/0x90
> vfs_write+0x14a/0x2a0
> ksys_write+0xa2/0x170
> do_syscall_64+0x7f/0x200
> entry_SYSCALL_64_after_hwframe+0x49/0xbe
>
> Fixes: 0597c49c69d5 ("tracing/uprobes: Use dyn_event framework for uprobe
> events")
> Signed-off-by: Eiichi Tsukata <de...@etsukata.com>
> ---
> kernel/trace/trace_uprobe.c | 13 ++++++++++---
> 1 file changed, 10 insertions(+), 3 deletions(-)
>
Good Catch.
Reviewed-by: Srikar Dronamraju <sri...@linux.vnet.ibm.com>
--
Thanks and Regards
Srikar Dronamraju
