From f48ecd38cb86b86f01914e875d74c92c077bf493 Mon Sep 17 00:00:00 2001 From: Jeff King Date: Wed, 13 Sep 2017 14:47:22 -0400 Subject: [PATCH] read_pack_header: handle signed/unsigned comparison in read result The result of read_in_full() may be -1 if we saw an error. But in comparing it to a sizeof() result, that "-1" will be promoted to size_t. In fact, the largest possible size_t which is much bigger than our struct size. This means that our "< sizeof(header)" error check won't trigger. In practice, we'd go on to read uninitialized memory and compare it to the PACK signature, which is likely to fail. But we shouldn't get there. We can fix this by making a direct "!=" comparison to the requested size, rather than "<". This means that errors get lumped in with short reads, but that's sufficient for our purposes here. There's no PH_ERROR tp represent our case. And anyway, this function reads from pipes and network sockets. A network error may racily appear as EOF to us anyway if there's data left in the socket buffers. Signed-off-by: Jeff King Reviewed-by: Jonathan Nieder Signed-off-by: Junio C Hamano --- sha1_file.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/sha1_file.c b/sha1_file.c index 4fa4b185f3..20a9d39c00 100644 --- a/sha1_file.c +++ b/sha1_file.c @@ -3722,7 +3722,7 @@ int index_path(unsigned char *sha1, const char *path, struct stat *st, unsigned int read_pack_header(int fd, struct pack_header *header) { - if (read_in_full(fd, header, sizeof(*header)) < sizeof(*header)) + if (read_in_full(fd, header, sizeof(*header)) != sizeof(*header)) /* "eof before pack header was fully read" */ return PH_ERROR_EOF; -- 2.47.1