From 509da98991e2a3f72042c6b29e538a5269357a80 Mon Sep 17 00:00:00 2001 From: "Darrick J. Wong" Date: Sun, 6 Jul 2025 11:31:00 -0700 Subject: [PATCH] libext2fs: fix off-by-one bug in punch_extent_blocks punch_extent_blocks tries to validate its input parameters to make sure that the physical range of blocks being punched do not go past the end of the filesystem. Unfortunately, there's an off-by-one bug in the valiation, because start==0 count==10 is a perfectly valid range on a 10-block filesystem. Cc: linux-ext4@vger.kernel.org # v1.46.6 Fixes: 6772d4969e9c90 ("libext2fs: check for invalid blocks in ext2fs_punch_blocks()") Signed-off-by: Darrick J. Wong Link: https://lore.kernel.org/r/175182662987.1984706.5292286424808159532.stgit@frogsfrogsfrogs Signed-off-by: Theodore Ts'o --- lib/ext2fs/punch.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/lib/ext2fs/punch.c b/lib/ext2fs/punch.c index 80c699eb..19b6a378 100644 --- a/lib/ext2fs/punch.c +++ b/lib/ext2fs/punch.c @@ -201,7 +201,7 @@ static errcode_t punch_extent_blocks(ext2_filsys fs, ext2_ino_t ino, errcode_t retval = 0; if (free_start < fs->super->s_first_data_block || - (free_start + free_count) >= ext2fs_blocks_count(fs->super)) + (free_start + free_count) > ext2fs_blocks_count(fs->super)) return EXT2_ET_BAD_BLOCK_NUM; /* No bigalloc? Just free each block. */ -- 2.47.2