[PATCH RESEND] fs/befs: fix shift-out-of-bounds in befs_check_sb
From: Manas Ghandat <hidden>
Date: 2023-08-01 15:59:20
Also in:
lkml
Subsystem:
befs file system, filesystems (vfs and infrastructure), the rest · Maintainers:
Luis de Bethencourt, Salah Triki, Alexander Viro, Christian Brauner, Linus Torvalds
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 <redacted> --- 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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