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authorHarshad Shirwadkar <harshadshirwadkar@gmail.com>2020-04-20 19:39:59 -0700
committerTheodore Ts'o <tytso@mit.edu>2020-06-03 23:16:49 -0400
commitc36a71b4e35ab35340facdd6964a00956b9fef0a (patch)
treebd5d5792db46bc4e03233af0e696601e56385e14 /fs/ext4/ext4_extents.h
parent39c0ae163f3b3ae691e7cce226ba1984ef6456b1 (diff)
downloadlinux-c36a71b4e35ab35340facdd6964a00956b9fef0a.tar.gz
ext4: fix EXT_MAX_EXTENT/INDEX to check for zeroed eh_max
If eh->eh_max is 0, EXT_MAX_EXTENT/INDEX would evaluate to unsigned (-1) resulting in illegal memory accesses. Although there is no consistent repro, we see that generic/019 sometimes crashes because of this bug. Ran gce-xfstests smoke and verified that there were no regressions. Signed-off-by: Harshad Shirwadkar <harshadshirwadkar@gmail.com> Link: https://lore.kernel.org/r/20200421023959.20879-2-harshadshirwadkar@gmail.com Signed-off-by: Theodore Ts'o <tytso@mit.edu> Cc: stable@kernel.org
Diffstat (limited to 'fs/ext4/ext4_extents.h')
-rw-r--r--fs/ext4/ext4_extents.h9
1 files changed, 6 insertions, 3 deletions
diff --git a/fs/ext4/ext4_extents.h b/fs/ext4/ext4_extents.h
index 1c216fcc202ad4..44e59881a1f0b5 100644
--- a/fs/ext4/ext4_extents.h
+++ b/fs/ext4/ext4_extents.h
@@ -170,10 +170,13 @@ struct partial_cluster {
(EXT_FIRST_EXTENT((__hdr__)) + le16_to_cpu((__hdr__)->eh_entries) - 1)
#define EXT_LAST_INDEX(__hdr__) \
(EXT_FIRST_INDEX((__hdr__)) + le16_to_cpu((__hdr__)->eh_entries) - 1)
-#define EXT_MAX_EXTENT(__hdr__) \
- (EXT_FIRST_EXTENT((__hdr__)) + le16_to_cpu((__hdr__)->eh_max) - 1)
+#define EXT_MAX_EXTENT(__hdr__) \
+ ((le16_to_cpu((__hdr__)->eh_max)) ? \
+ ((EXT_FIRST_EXTENT((__hdr__)) + le16_to_cpu((__hdr__)->eh_max) - 1)) \
+ : 0)
#define EXT_MAX_INDEX(__hdr__) \
- (EXT_FIRST_INDEX((__hdr__)) + le16_to_cpu((__hdr__)->eh_max) - 1)
+ ((le16_to_cpu((__hdr__)->eh_max)) ? \
+ ((EXT_FIRST_INDEX((__hdr__)) + le16_to_cpu((__hdr__)->eh_max) - 1)) : 0)
static inline struct ext4_extent_header *ext_inode_hdr(struct inode *inode)
{