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author | Masami Hiramatsu <mhiramat@kernel.org> | 2019-11-27 08:57:04 +0300 |
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committer | Ingo Molnar <mingo@kernel.org> | 2019-11-27 09:44:25 +0300 |
commit | f66c0447cca1281116224d474cdb37d6a18e4b5b (patch) | |
tree | d63b3bb3473ed46c241ba7dbe35f389535eba1fb /arch/nds32/include | |
parent | 285a54efe3861976af9d15e85ff8c91a78d1407b (diff) | |
download | linux-f66c0447cca1281116224d474cdb37d6a18e4b5b.tar.xz |
kprobes: Set unoptimized flag after unoptimizing code
Set the unoptimized flag after confirming the code is completely
unoptimized. Without this fix, when a kprobe hits the intermediate
modified instruction (the first byte is replaced by an INT3, but
later bytes can still be a jump address operand) while unoptimizing,
it can return to the middle byte of the modified code, which causes
an invalid instruction exception in the kernel.
Usually, this is a rare case, but if we put a probe on the function
call while text patching, it always causes a kernel panic as below:
# echo p text_poke+5 > kprobe_events
# echo 1 > events/kprobes/enable
# echo 0 > events/kprobes/enable
invalid opcode: 0000 [#1] PREEMPT SMP PTI
RIP: 0010:text_poke+0x9/0x50
Call Trace:
arch_unoptimize_kprobe+0x22/0x28
arch_unoptimize_kprobes+0x39/0x87
kprobe_optimizer+0x6e/0x290
process_one_work+0x2a0/0x610
worker_thread+0x28/0x3d0
? process_one_work+0x610/0x610
kthread+0x10d/0x130
? kthread_park+0x80/0x80
ret_from_fork+0x3a/0x50
text_poke() is used for patching the code in optprobes.
This can happen even if we blacklist text_poke() and other functions,
because there is a small time window during which we show the intermediate
code to other CPUs.
[ mingo: Edited the changelog. ]
Tested-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: bristot@redhat.com
Fixes: 6274de4984a6 ("kprobes: Support delayed unoptimizing")
Link: https://lkml.kernel.org/r/157483422375.25881.13508326028469515760.stgit@devnote2
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Diffstat (limited to 'arch/nds32/include')
0 files changed, 0 insertions, 0 deletions