From: Yichao Yu <yyc1992@gmail.com>
To: gdb@sourceware.org
Subject: Suspected bug in DW_OP_addr handling
Date: Fri, 6 May 2022 23:54:19 -0400 [thread overview]
Message-ID: <CAMvDr+TO9MOCsksFfDnMuDtctc3vxe6pRmNpRmsZgpDk5wLzYg@mail.gmail.com> (raw)
I noticed that gdb unwind failed with read of invalid memory address
when I used `DW_OP_addr` in my unwind info. Upon checking, it seems
that the handling of this operation in the dwarf interpreter is very
suspicious.
The interpreter for the op code has a comment[1] sayijng,
> Some versions of GCC emit DW_OP_addr before
> DW_OP_GNU_push_tls_address. In this case the value is an
> index, not an address.
However, the code appears to check for exactly the opposite condition
`op_ptr >= op_end || *op_ptr != DW_OP_GNU_push_tls_address` to decide
whether the result should be used as index. This was added 12 years
ago in commit ac56253ddece [2].
Am I missing something or is this a long-standing bug?
Yichao
[1] https://github.com/bminor/binutils-gdb/blob/2392dc0f8e243a4f5f9d0db6cee64a1698886e56/gdb/dwarf2/expr.c#L1574-L1585
[2] https://github.com/bminor/binutils-gdb/commit/ac56253ddece35aff4402b848f88ba40856102b1#diff-9c28445d6bd87cff9dcb11dc4b58ff0e605a078b08ceb37da22d8d2c7b866f6aR406
next reply other threads:[~2022-05-07 3:54 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-05-07 3:54 Yichao Yu [this message]
2022-05-08 17:25 ` Simon Marchi
2022-05-09 14:03 ` Yichao Yu
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