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index: be careful when handling long names

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We currently use lower 12-bit (masked with CE_NAMEMASK) in the
ce_flags field to store the length of the name in cache_entry,
without checking the length parameter given to
create_ce_flags().  This can make us store incorrect length.

Currently we are mostly protected by the fact that many
codepaths first copy the path in a variable of size PATH_MAX,
which typically is 4096 that happens to match the limit, but
that feels like a bug waiting to happen.  Besides, that would
not allow us to shorten the width of CE_NAMEMASK to use the bits
for new flags.

This redefines the meaning of the name length stored in the
cache_entry.  A name that does not fit is represented by storing
CE_NAMEMASK in the field, and the actual length needs to be
computed by actually counting the bytes in the name[] field.
This way, only the unusually long paths need to suffer.

Signed-off-by: Junio C Hamano <gitster@pobox.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Junio C Hamano
2008-01-18 23:42:00 -08:00
committed by Linus Torvalds
parent 7a51ed66f6
commit 7fec10b7f4
3 changed files with 46 additions and 3 deletions
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12
read-cache.c
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@ -928,6 +928,8 @@ int read_index(struct index_state *istate)
static void convert_from_disk(struct ondisk_cache_entry *ondisk, struct cache_entry *ce)
{
size_t len;
ce->ce_ctime = ntohl(ondisk->ctime.sec);
ce->ce_mtime = ntohl(ondisk->mtime.sec);
ce->ce_dev = ntohl(ondisk->dev);
@ -939,7 +941,15 @@ static void convert_from_disk(struct ondisk_cache_entry *ondisk, struct cache_en
/* On-disk flags are just 16 bits */
ce->ce_flags = ntohs(ondisk->flags);
hashcpy(ce->sha1, ondisk->sha1);
memcpy(ce->name, ondisk->name, ce_namelen(ce)+1);
len = ce->ce_flags & CE_NAMEMASK;
if (len == CE_NAMEMASK)
len = strlen(ondisk->name);
/*
* NEEDSWORK: If the original index is crafted, this copy could
* go unchecked.
*/
memcpy(ce->name, ondisk->name, len + 1);
}
/* remember to discard_cache() before reading a different cache! */