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libbacktrace: add casts to avoid undefined shifts

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Patch from pgerell@github.

	* elf.c (elf_fetch_bits): Add casts to avoid potentially shifting
	a value farther than its type size.
	(elf_fetch_bits_backward): Likewise.
	(elf_uncompress_lzma_block): Likewise.
	(elf_uncompress_lzma): Likewise.
This commit is contained in:
Ian Lance Taylor
2025-01-30 15:20:23 -08:00
parent 5da31b9952
commit 78af4ffa26
1 changed files with 20 additions and 14 deletions
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34
elf.c
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@@ -1147,7 +1147,10 @@ elf_fetch_bits (const unsigned char **ppin, const unsigned char *pinend,
next = __builtin_bswap32 (next); next = __builtin_bswap32 (next);
#endif #endif
#else #else
next = pin[0] | (pin[1] << 8) | (pin[2] << 16) | (pin[3] << 24); next = ((uint32_t)pin[0]
| ((uint32_t)pin[1] << 8)
| ((uint32_t)pin[2] << 16)
| ((uint32_t)pin[3] << 24));
#endif #endif
val |= (uint64_t)next << bits; val |= (uint64_t)next << bits;
@@ -1198,7 +1201,10 @@ elf_fetch_bits_backward (const unsigned char **ppin,
next = __builtin_bswap32 (next); next = __builtin_bswap32 (next);
#endif #endif
#else #else
next = pin[0] | (pin[1] << 8) | (pin[2] << 16) | (pin[3] << 24); next = ((uint32_t)pin[0]
| ((uint32_t)pin[1] << 8)
| ((uint32_t)pin[2] << 16)
| ((uint32_t)pin[3] << 24));
#endif #endif
val <<= 32; val <<= 32;
@@ -5872,10 +5878,10 @@ elf_uncompress_lzma_block (const unsigned char *compressed,
/* The byte at compressed[off] is ignored for some /* The byte at compressed[off] is ignored for some
reason. */ reason. */
code = ((compressed[off + 1] << 24) code = ((uint32_t)(compressed[off + 1] << 24)
+ (compressed[off + 2] << 16) + ((uint32_t)compressed[off + 2] << 16)
+ (compressed[off + 3] << 8) + ((uint32_t)compressed[off + 3] << 8)
+ compressed[off + 4]); + (uint32_t)compressed[off + 4]);
off += 5; off += 5;
/* This is the main LZMA decode loop. */ /* This is the main LZMA decode loop. */
@@ -6198,10 +6204,10 @@ elf_uncompress_lzma_block (const unsigned char *compressed,
return 0; return 0;
} }
computed_crc = elf_crc32 (0, uncompressed, uncompressed_offset); computed_crc = elf_crc32 (0, uncompressed, uncompressed_offset);
stream_crc = (compressed[off] stream_crc = ((uint32_t)compressed[off]
| (compressed[off + 1] << 8) | ((uint32_t)compressed[off + 1] << 8)
| (compressed[off + 2] << 16) | ((uint32_t)compressed[off + 2] << 16)
| (compressed[off + 3] << 24)); | ((uint32_t)compressed[off + 3] << 24));
if (computed_crc != stream_crc) if (computed_crc != stream_crc)
{ {
elf_uncompress_failed (); elf_uncompress_failed ();
@@ -6336,10 +6342,10 @@ elf_uncompress_lzma (struct backtrace_state *state,
/* Before that is the size of the index field, which precedes the /* Before that is the size of the index field, which precedes the
footer. */ footer. */
index_size = (compressed[offset - 4] index_size = ((size_t)compressed[offset - 4]
| (compressed[offset - 3] << 8) | ((size_t)compressed[offset - 3] << 8)
| (compressed[offset - 2] << 16) | ((size_t)compressed[offset - 2] << 16)
| (compressed[offset - 1] << 24)); | ((size_t)compressed[offset - 1] << 24));
index_size = (index_size + 1) * 4; index_size = (index_size + 1) * 4;
offset -= 4; offset -= 4;