packfile.c: prevent overflow in `load_idx()`
Prevent an overflow when locating a pack's CRC offset when the number of packed items is greater than 2^32-1/hashsz by guarding the computation with an `st_mult()`. Note that to avoid truncating the result, the `crc_offset` member must itself become a `size_t`. The only usage of this variable (besides the assignment in `load_idx()`) is in `read_v2_anomalous_offsets()` in the index-pack code. There we use the `crc_offset` as a pointer offset, so we are already equipped to handle the type change. Helped-by: Phillip Wood <phillip.wood@dunelm.org.uk> Signed-off-by: Taylor Blau <me@ttaylorr.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>
Taylor Blau committed
Jul 13, 2023 at 20:54 UTC
42be681b33ef73be056fb99e3c63c6e9b9c2e7ef
2 files changed
+2
-2
object-store.h
+1
-1
@@ -110,7 +110,7 @@ struct packed_git {
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const void *index_data;
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size_t index_size;
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uint32_t num_objects;
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- uint32_t crc_offset;
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+ size_t crc_offset;
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struct oidset bad_objects;
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int index_version;
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time_t mtime;
packfile.c
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-1
@@ -186,7 +186,7 @@ int load_idx(const char *path, const unsigned int hashsz, void *idx_map,
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*/
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(sizeof(off_t) <= 4))
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return error("pack too large for current definition of off_t in %s", path);
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- p->crc_offset = 8 + 4 * 256 + nr * hashsz;
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+ p->crc_offset = st_add(8 + 4 * 256, st_mult(nr, hashsz));
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}
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p->index_version = version;