libbacktrace: don't assume compressed section is aligned

Patch originally by GitHub user ubyte at
https://github.com/ianlancetaylor/libbacktrace/pull/120.

	* elf.c (elf_uncompress_chdr): Don't assume compressed section is
	aligned.
This commit is contained in:
Ian Lance Taylor 2024-03-08 13:55:34 -08:00
parent cebbaa2a84
commit 5825bd0e0d

View File

@ -5076,7 +5076,7 @@ elf_uncompress_chdr (struct backtrace_state *state,
backtrace_error_callback error_callback, void *data,
unsigned char **uncompressed, size_t *uncompressed_size)
{
const b_elf_chdr *chdr;
b_elf_chdr chdr;
char *alc;
size_t alc_len;
unsigned char *po;
@ -5088,27 +5088,30 @@ elf_uncompress_chdr (struct backtrace_state *state,
if (compressed_size < sizeof (b_elf_chdr))
return 1;
chdr = (const b_elf_chdr *) compressed;
/* The lld linker can misalign a compressed section, so we can't safely read
the fields directly as we can for other ELF sections. See
https://github.com/ianlancetaylor/libbacktrace/pull/120. */
memcpy (&chdr, compressed, sizeof (b_elf_chdr));
alc = NULL;
alc_len = 0;
if (*uncompressed != NULL && *uncompressed_size >= chdr->ch_size)
if (*uncompressed != NULL && *uncompressed_size >= chdr.ch_size)
po = *uncompressed;
else
{
alc_len = chdr->ch_size;
alc_len = chdr.ch_size;
alc = backtrace_alloc (state, alc_len, error_callback, data);
if (alc == NULL)
return 0;
po = (unsigned char *) alc;
}
switch (chdr->ch_type)
switch (chdr.ch_type)
{
case ELFCOMPRESS_ZLIB:
if (!elf_zlib_inflate_and_verify (compressed + sizeof (b_elf_chdr),
compressed_size - sizeof (b_elf_chdr),
zdebug_table, po, chdr->ch_size))
zdebug_table, po, chdr.ch_size))
goto skip;
break;
@ -5116,7 +5119,7 @@ elf_uncompress_chdr (struct backtrace_state *state,
if (!elf_zstd_decompress (compressed + sizeof (b_elf_chdr),
compressed_size - sizeof (b_elf_chdr),
(unsigned char *)zdebug_table, po,
chdr->ch_size))
chdr.ch_size))
goto skip;
break;
@ -5126,7 +5129,7 @@ elf_uncompress_chdr (struct backtrace_state *state,
}
*uncompressed = po;
*uncompressed_size = chdr->ch_size;
*uncompressed_size = chdr.ch_size;
return 1;
@ -6876,8 +6879,8 @@ elf_add (struct backtrace_state *state, const char *filename, int descriptor,
}
}
// A debuginfo file may not have a useful .opd section, but we can use the
// one from the original executable.
/* A debuginfo file may not have a useful .opd section, but we can use the
one from the original executable. */
if (opd == NULL)
opd = caller_opd;