Commits
Andrea Righi committed 8b05a3a7503
tracing/kprobes: Fix NULL pointer dereference in trace_kprobe_create()
It is possible to trigger a NULL pointer dereference by writing an
incorrectly formatted string to krpobe_events (trying to create a
kretprobe omitting the symbol).
Example:
echo "r:event_1 " >> /sys/kernel/debug/tracing/kprobe_events
That triggers this:
BUG: unable to handle kernel NULL pointer dereference at 0000000000000000
#PF error: [normal kernel read fault]
PGD 0 P4D 0
Oops: 0000 [#1] SMP PTI
CPU: 6 PID: 1757 Comm: bash Not tainted 5.0.0-rc1+ #125
Hardware name: Dell Inc. XPS 13 9370/0F6P3V, BIOS 1.5.1 08/09/2018
RIP: 0010:kstrtoull+0x2/0x20
Code: 28 00 00 00 75 17 48 83 c4 18 5b 41 5c 5d c3 b8 ea ff ff ff eb e1 b8 de ff ff ff eb da e8 d6 36 bb ff 66 0f 1f 44 00 00 31 c0 <80> 3f 2b 55 48 89 e5 0f 94 c0 48 01 c7 e8 5c ff ff ff 5d c3 66 2e
RSP: 0018:ffffb5d482e57cb8 EFLAGS: 00010246
RAX: 0000000000000000 RBX: 0000000000000001 RCX: ffffffff82b12720
RDX: ffffb5d482e57cf8 RSI: 0000000000000000 RDI: 0000000000000000
RBP: ffffb5d482e57d70 R08: ffffa0c05e5a7080 R09: ffffa0c05e003980
R10: 0000000000000000 R11: 0000000040000000 R12: ffffa0c04fe87b08
R13: 0000000000000001 R14: 000000000000000b R15: ffffa0c058d749e1
FS: 00007f137c7f7740(0000) GS:ffffa0c05e580000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000000000000000 CR3: 0000000497d46004 CR4: 00000000003606e0
Call Trace:
? trace_kprobe_create+0xb6/0x840
? _cond_resched+0x19/0x40
? _cond_resched+0x19/0x40
? __kmalloc+0x62/0x210
? argv_split+0x8f/0x140
? trace_kprobe_create+0x840/0x840
? trace_kprobe_create+0x840/0x840
create_or_delete_trace_kprobe+0x11/0x30
trace_run_command+0x50/0x90
trace_parse_run_command+0xc1/0x160
probes_write+0x10/0x20
__vfs_write+0x3a/0x1b0
? apparmor_file_permission+0x1a/0x20
? security_file_permission+0x31/0xf0
? _cond_resched+0x19/0x40
vfs_write+0xb1/0x1a0
ksys_write+0x55/0xc0
__x64_sys_write+0x1a/0x20
do_syscall_64+0x5a/0x120
entry_SYSCALL_64_after_hwframe+0x44/0xa9
Fix by doing the proper argument checks in trace_kprobe_create().
Cc: Ingo Molnar <mingo@redhat.com>
Link: https://lore.kernel.org/lkml/20190111095108.b79a2ee026185cbd62365977@kernel.org
Link: http://lkml.kernel.org/r/20190111060113.GA22841@xps-13
Fixes: 6212dd29683e ("tracing/kprobes: Use dyn_event framework for kprobe events")
Acked-by: Masami Hiramatsu <mhiramat@kernel.org>
Signed-off-by: Andrea Righi <righi.andrea@gmail.com>
Signed-off-by: Masami Hiramatsu <mhiramat@kernel.org>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>