Messages in this thread Patch in this message | | | From | Manas Ghandat <> | Subject | [PATCH RESEND] fs/befs: fix shift-out-of-bounds in befs_check_sb | Date | Tue, 1 Aug 2023 21:28:23 +0530 |
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The consistency check for the block_size by using the block_shift caused integer overflow. Thus a max limit to the block_shift was defined named BEFS_MAX_BLOCK_SHIFT in befs.h. Also check for the block_shift was added so that overflow does not occur.
Reported-by: syzbot+fc26c366038b54261e53@syzkaller.appspotmail.com
Signed-off-by: Manas Ghandat <ghandatmanas@gmail.com> --- fs/befs/befs.h | 2 +- fs/befs/super.c | 11 +++++++++++ 2 files changed, 13 insertions(+), 2 deletions(-)
diff --git a/fs/befs/befs.h b/fs/befs/befs.h index 7cd47245694d..5490024adb33 100644 --- a/fs/befs/befs.h +++ b/fs/befs/befs.h @@ -13,7 +13,7 @@ /* used in debug.c */ #define BEFS_VERSION "0.9.3" - +#define BEFS_MAX_BLOCK_SHIFT 31 typedef u64 befs_blocknr_t; /* diff --git a/fs/befs/super.c b/fs/befs/super.c index 7c50025c99d8..f2aeb2ed6e77 100644 --- a/fs/befs/super.c +++ b/fs/befs/super.c @@ -88,6 +88,17 @@ befs_check_sb(struct super_block *sb) return BEFS_ERR; } + /* + * block_shift check added so that overflow does not + * occur during the block_size check + */ + + if (befs_sb->block_shift > BEFS_MAX_BLOCK_SHIFT) { + befs_error(sb, "block_size too large. " + "Corruption likely."); + return BEFS_ERR; + } + /* * block_shift and block_size encode the same information * in different ways as a consistency check. -- 2.37.2
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