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.
Signed-off-by: Manas Ghandat <ghandatmanas@gmail.com>
---
fs/befs/befs.h | 4 ++--
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;
/*
@@ -133,7 +133,7 @@ blockno2iaddr(struct super_block *sb, befs_blocknr_t blockno)
iaddr.allocation_group = blockno >> BEFS_SB(sb)->ag_shift;
iaddr.start =
- blockno - (iaddr.allocation_group << BEFS_SB(sb)->ag_shift);
+ blockno - (iaddr.allocation_group << BEFS_SB(sb)->ag_shift);
iaddr.len = 1;
return iaddr;
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