From 619faec7a2f51d178d1d48f405d5dd8ef3862c6c Mon Sep 17 00:00:00 2001 From: Filipe Manana Date: Thu, 17 Feb 2022 12:12:08 +0000 Subject: [PATCH] btrfs: deal with unexpected extent type during reflinking Smatch complains about a possible dereference of a pointer that was not initialized: CC [M] fs/btrfs/reflink.o CHECK fs/btrfs/reflink.c fs/btrfs/reflink.c:533 btrfs_clone() error: potentially dereferencing uninitialized 'trans'. This is because we are not dealing with the case where the type of a file extent has an unexpected value (not regular, not prealloc and not inline), in which case the transaction handle pointer is not initialized. Such unexpected type should be impossible, except in case of some memory corruption caused either by bad hardware or some software bug causing something like a buffer overrun. So ASSERT that if the extent type is neither regular nor prealloc, then it must be inline. Bail out with -EUCLEAN and a warning in case it is not. This silences smatch. Signed-off-by: Filipe Manana Signed-off-by: David Sterba --- fs/btrfs/reflink.c | 6 ++++-- 1 file changed, 4 insertions(+), 2 deletions(-) diff --git a/fs/btrfs/reflink.c b/fs/btrfs/reflink.c index 07e19e069c84c..03d60db0c5a34 100644 --- a/fs/btrfs/reflink.c +++ b/fs/btrfs/reflink.c @@ -494,7 +494,8 @@ process_slot: &clone_info, &trans); if (ret) goto out; - } else if (type == BTRFS_FILE_EXTENT_INLINE) { + } else { + ASSERT(type == BTRFS_FILE_EXTENT_INLINE); /* * Inline extents always have to start at file offset 0 * and can never be bigger then the sector size. We can @@ -505,7 +506,8 @@ process_slot: */ ASSERT(key.offset == 0); ASSERT(datal <= fs_info->sectorsize); - if (WARN_ON(key.offset != 0) || + if (WARN_ON(type != BTRFS_FILE_EXTENT_INLINE) || + WARN_ON(key.offset != 0) || WARN_ON(datal > fs_info->sectorsize)) { ret = -EUCLEAN; goto out; -- 2.39.5