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| author | Keith Randall <khr@golang.org> | 2023-05-09 15:55:45 -0700 |
|---|---|---|
| committer | Keith Randall <khr@golang.org> | 2023-05-10 04:57:07 +0000 |
| commit | 5d76600cc01790c0eed9d0e2783ecf5bc7957993 (patch) | |
| tree | 16bef397f641a25043bcdc3eea038e1ed4ee1cd4 | |
| parent | aa4d5e739f32397969fd5c33cbc95d316686039f (diff) | |
| download | go-5d76600cc01790c0eed9d0e2783ecf5bc7957993.tar.xz | |
runtime: fix misaligned SP for libfuzzer entry
libfuzzer is written in C and so requires by the C abi that SP be
aligned correctly mod 16. Normally CALLs need to have SP aligned to 0
mod 16, but because we're simulating a CALL (which pushes a return
address) with a JMP (which doesn't), we need to align to 8 mod 16
before JMPing.
This is not causing any current problems that I know of. All the
functions called from this callsite that I checked don't rely on
correct alignment. So this CL is just futureproofing.
Update #49075
Change-Id: I13fcbe9aaf2853056a6d44dc3aa64b7db689e144
Reviewed-on: https://go-review.googlesource.com/c/go/+/494117
Reviewed-by: Cherry Mui <cherryyz@google.com>
TryBot-Result: Gopher Robot <gobot@golang.org>
Run-TryBot: Keith Randall <khr@golang.org>
Reviewed-by: Keith Randall <khr@google.com>
| -rw-r--r-- | src/runtime/libfuzzer_amd64.s | 1 |
1 files changed, 1 insertions, 0 deletions
diff --git a/src/runtime/libfuzzer_amd64.s b/src/runtime/libfuzzer_amd64.s index 7f184d9cb6..e30b768a05 100644 --- a/src/runtime/libfuzzer_amd64.s +++ b/src/runtime/libfuzzer_amd64.s @@ -93,6 +93,7 @@ TEXT runtime·libfuzzerCallTraceIntCmp(SB), NOSPLIT, $0-32 MOVQ (g_sched+gobuf_sp)(R10), SP call: ANDQ $~15, SP // alignment for gcc ABI + SUBQ $8, SP // Load the address of the end of the function and push it into the stack. // This address will be jumped to after executing the return instruction // from the return sled. There we reset the stack pointer and return. |