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sha1_loose_object_info: return error for corrupted objects 

When sha1_loose_object_info() finds that a loose object file
cannot be stat(2)ed or mmap(2)ed, it returns -1 to signal an
error to the caller.  However, if it found that the loose
object file is corrupt and the object data cannot be used
from it, it stuffs OBJ_BAD into "type" field of the
object_info, but returns zero (i.e., success), which can
confuse callers.

This is due to 052fe5eac (sha1_loose_object_info: make type
lookup optional, 2013-07-12), which switched the return to a
strict success/error, rather than returning the type (but
botched the return).

Callers of regular sha1_object_info() don't notice the
difference, as that function returns the type (which is
OBJ_BAD in this case). However, direct callers of
sha1_object_info_extended() see the function return success,
but without setting any meaningful values in the object_info
struct, leading them to access potentially uninitialized
memory.

The easiest way to see the bug is via "cat-file -s", which
will happily ignore the corruption and report whatever
value happened to be in the "size" variable.

Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
This commit is contained in:
Jeff King 2017-04-01 04:05:21 -04:00 committed by Junio C Hamano
parent 49800c9407
commit 93cff9a978
2 changed files with 8 additions and 1 deletions
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2
sha1_file.c
View File

@ -2867,7 +2867,7 @@ static int sha1_loose_object_info(const unsigned char *sha1,
if (status && oi->typep)
*oi->typep = status;
strbuf_release(&hdrbuf);
return 0;
return (status < 0) ? status : 0;
}
int sha1_object_info_extended(const unsigned char *sha1, struct object_info *oi, unsigned flags)

7
t/t1060-object-corruption.sh
View File

@ -53,6 +53,13 @@ test_expect_success 'streaming a corrupt blob fails' '
)
'
test_expect_success 'getting type of a corrupt blob fails' '
(
cd bit-error &&
test_must_fail git cat-file -s HEAD:content.t
)
'
test_expect_success 'read-tree -u detects bit-errors in blobs' '
(
cd bit-error &&