ag_shift is used by blockno2iaddr() to get allocation group number from block. If ag_shift is inconsistent with block_per_ag, an out of bounds allocation group may occur [1]. So add return BEFS_ERR and update comment and error message to reflect this change.
[1] https://lkml.org/lkml/2016/8/12/42 Signed-off-by: Salah Triki <[email protected]> --- fs/befs/super.c | 9 ++++++--- 1 file changed, 6 insertions(+), 3 deletions(-) diff --git a/fs/befs/super.c b/fs/befs/super.c index 7c50025..2e3a3fd 100644 --- a/fs/befs/super.c +++ b/fs/befs/super.c @@ -101,10 +101,13 @@ befs_check_sb(struct super_block *sb) /* ag_shift also encodes the same information as blocks_per_ag in a - * different way, non-fatal consistency check + * different way as a consistency check. */ - if ((1 << befs_sb->ag_shift) != befs_sb->blocks_per_ag) - befs_error(sb, "ag_shift disagrees with blocks_per_ag."); + if ((1 << befs_sb->ag_shift) != befs_sb->blocks_per_ag) { + befs_error(sb, "ag_shift disagrees with blocks_per_ag. " + "Corruption likely."); + return BEFS_ERR; + } if (befs_sb->log_start != befs_sb->log_end || befs_sb->flags == BEFS_DIRTY) { -- 1.9.1
