[llvm-dev] [ASAN] [Regression] Stack pointer corruption on ARMv7

[Vit “vit9696” U via llvm-dev]

Hello,

I discovered a stack pointer corruption regression in LLVM 13 causing stack leak with ASAN enabled when targeting cortex-a9.

The issue is reproducible with the file in the attachment. Also published online[1]. The arguments to compile are as follows:

clang -o error.o -c -target arm-gnu-linux-eabi -mcpu=cortex-a9 -fsanitize=address error.c

The problematic part is the loop in the `test` function. When `func` is called, LLVM does not adjust the stack back, causing fast stack overflow:

.LBB2_5:                                @ %for.cond
        ...
        sub     sp, sp, #8
        str     r12, [sp]
        bl      func
.LBB2_7:                                @ %if.end
        b       .LBB2_5

LLVM 12.0.1 does not have this issue. I will post the issue to the bugtracker when GitHub Issues land or bugzilla returns. Can anyone confirm that the issue is still present in main?

Best regards,
Vitaly

[1] https://godbolt.org/z/GjxqPfMW6

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