From b3118bdc91876cbc04b7e81dcf7bea71d86ce4f8 Mon Sep 17 00:00:00 2001 From: "Shawn O. Pearce" Date: Wed, 14 Oct 2009 07:23:51 -0700 Subject: [PATCH] sha1_file: Fix infinite loop when pack is corrupted Some types of corruption to a pack may confuse the deflate stream which stores an object. In Andy's reported case a 36 byte region of the pack was overwritten, leading to what appeared to be a valid deflate stream that was trying to produce a result larger than our allocated output buffer could accept. Z_BUF_ERROR is returned from inflate() if either the input buffer needs more input bytes, or the output buffer has run out of space. Previously we only considered the former case, as it meant we needed to move the stream's input buffer to the next window in the pack. We now abort the loop if inflate() returns Z_BUF_ERROR without consuming the entire input buffer it was given, or has filled the entire output buffer but has not yet returned Z_STREAM_END. Either state is a clear indicator that this loop is not working as expected, and should not continue. This problem cannot occur with loose objects as we open the entire loose object as a single buffer and treat Z_BUF_ERROR as an error. Reported-by: Andy Isaacson Signed-off-by: Shawn O. Pearce Acked-by: Nicolas Pitre Signed-off-by: Junio C Hamano --- sha1_file.c | 4 ++++ t/t5303-pack-corruption-resilience.sh | 9 +++++++++ 2 files changed, 13 insertions(+) diff --git a/sha1_file.c b/sha1_file.c index 4ea0b18d0..4cc8939e4 100644 --- a/sha1_file.c +++ b/sha1_file.c @@ -1357,6 +1357,8 @@ unsigned long get_size_from_delta(struct packed_git *p, in = use_pack(p, w_curs, curpos, &stream.avail_in); stream.next_in = in; st = git_inflate(&stream, Z_FINISH); + if (st == Z_BUF_ERROR && (stream.avail_in || !stream.avail_out)) + break; curpos += stream.next_in - in; } while ((st == Z_OK || st == Z_BUF_ERROR) && stream.total_out < sizeof(delta_head)); @@ -1594,6 +1596,8 @@ static void *unpack_compressed_entry(struct packed_git *p, in = use_pack(p, w_curs, curpos, &stream.avail_in); stream.next_in = in; st = git_inflate(&stream, Z_FINISH); + if (st == Z_BUF_ERROR && (stream.avail_in || !stream.avail_out)) + break; curpos += stream.next_in - in; } while (st == Z_OK || st == Z_BUF_ERROR); git_inflate_end(&stream); diff --git a/t/t5303-pack-corruption-resilience.sh b/t/t5303-pack-corruption-resilience.sh index 5132d4130..5f6cd4f33 100755 --- a/t/t5303-pack-corruption-resilience.sh +++ b/t/t5303-pack-corruption-resilience.sh @@ -275,4 +275,13 @@ test_expect_success \ git cat-file blob $blob_2 > /dev/null && git cat-file blob $blob_3 > /dev/null' +test_expect_success \ + 'corrupting header to have too small output buffer fails unpack' \ + 'create_new_pack && + git prune-packed && + printf "\262\001" | do_corrupt_object $blob_1 0 && + test_must_fail git cat-file blob $blob_1 > /dev/null && + test_must_fail git cat-file blob $blob_2 > /dev/null && + test_must_fail git cat-file blob $blob_3 > /dev/null' + test_done -- 2.30.2