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x86/alternatives: Fix int3 handling failure from broken text_poke array

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Since smp_text_poke_single() does not expect there is another
text_poke request is queued, it can make text_poke_array not
sorted or cause a buffer overflow on the text_poke_array.vec[].
This will cause an Oops in int3 because of bsearch failing;

   CPU 0                        CPU 1                      CPU 2
   -----                        -----                      -----

 smp_text_poke_batch_add()

			    smp_text_poke_single() <<-- Adds out of order

							<int3>
                                                	[Fails o find address
                                                        in text_poke_array ]
                                                        OOPS!

Or unhandled page fault because of a buffer overflow;

   CPU 0                        CPU 1
   -----                        -----

 smp_text_poke_batch_add() <<+
 ...                         |
 smp_text_poke_batch_add() <<-- Adds TEXT_POKE_ARRAY_MAX times.

			     smp_text_poke_single() {
			     	__smp_text_poke_batch_add() <<-- Adds entry at
								TEXT_POKE_ARRAY_MAX + 1

                		smp_text_poke_batch_finish()
                        	  [Unhandled page fault because
				   text_poke_array.nr_entries is
				   overwritten]
				   BUG!
			     }

Use smp_text_poke_batch_add() instead of __smp_text_poke_batch_add()
so that it correctly flush the queue if needed.

Closes: https://lore.kernel.org/all/CA+G9fYsLu0roY3DV=tKyqP7FEKbOEETRvTDhnpPxJGbA=Cg+4w@mail.gmail.com/
Fixes: c8976ade0c ("x86/alternatives: Simplify smp_text_poke_single() by using tp_vec and existing APIs")
Reported-by: Linux Kernel Functional Testing <lkft@linaro.org>
Signed-off-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Steven Rostedt (Google) <rostedt@goodmis.org>
Tested-by: Linux Kernel Functional Testing <lkft@linaro.org>
Link: https://lkml.kernel.org/r/\ 175020512308.3582717.13631440385506146631.stgit@mhiramat.tok.corp.google.com
This commit is contained in:
Masami Hiramatsu (Google) 2025-06-18 09:05:23 +09:00 committed by Peter Zijlstra
parent cb6075bc62
commit 2aebf5ee43
1 changed files with 1 additions and 1 deletions
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2
arch/x86/kernel/alternative.c
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@ -3138,6 +3138,6 @@ void __ref smp_text_poke_batch_add(void *addr, const void *opcode, size_t len, c
*/
void __ref smp_text_poke_single(void *addr, const void *opcode, size_t len, const void *emulate)
{
__smp_text_poke_batch_add(addr, opcode, len, emulate);
smp_text_poke_batch_add(addr, opcode, len, emulate);
smp_text_poke_batch_finish();
}