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When nzones is 0, adfs_read_map() passes it to kmalloc_array(0, ...) which returns ZERO_SIZE_PTR, and adfs_map_layout() then writes to dm[-1], causing an out-of-bounds write before the allocated buffer. adfs_validate_dr0() already rejects nzones != 1 for old-format images. Add the equivalent check to adfs_validate_bblk() for new-format images so that a crafted image with nzones == 0 is rejected at probe time. Found by syzkaller. Fixes: f6f14a0d71b0 ("fs/adfs: map: move map-specific sb initialisation to map.c") Signed-off-by: Bae Yeonju --- Changes in v3: - Drop redundant Tested-by Changes in v2: - Move check from adfs_read_map() to adfs_validate_bblk() (Russell King) fs/adfs/super.c | 3 +++ 1 file changed, 3 insertions(+) diff --git a/fs/adfs/super.c b/fs/adfs/super.c index 4d3015e3a..b5522b862 100644 --- a/fs/adfs/super.c +++ b/fs/adfs/super.c @@ -343,6 +343,9 @@ static int adfs_validate_bblk(struct super_block *sb, struct buffer_head *bh, if (adfs_checkdiscrecord(dr)) return -EILSEQ; + if ((dr->nzones | dr->nzones_high << 8) == 0) + return -EILSEQ; + *drp = dr; return 0; } -- 2.43.0