6.17-stable review patch. If anyone has any objections, please let me know.
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From: Gao Xiang hsiangkao@linux.alibaba.com
[ Upstream commit a429b76114aaca3ef1aff4cd469dcf025431bd11 ]
Robert recently reported two corrupted images that can cause system crashes, which are related to the new encoded extents introduced in Linux 6.15:
- The first one [1] has plen != 0 (e.g. plen == 0x2000000) but (plen & Z_EROFS_EXTENT_PLEN_MASK) == 0. It is used to represent special extents such as sparse extents (!EROFS_MAP_MAPPED), but previously only plen == 0 was handled;
- The second one [2] has pa 0xffffffffffdcffed and plen 0xb4000, then "cur [0xfffffffffffff000] += bvec.bv_len [0x1000]" in "} while ((cur += bvec.bv_len) < end);" wraps around, causing an out-of-bound access of pcl->compressed_bvecs[] in z_erofs_submit_queue(). EROFS only supports 48-bit physical block addresses (up to 1EiB for 4k blocks), so add a sanity check to enforce this.
Fixes: 1d191b4ca51d ("erofs: implement encoded extent metadata") Reported-by: Robert Morris rtm@csail.mit.edu Closes: https://lore.kernel.org/r/75022.1759355830@localhost [1] Closes: https://lore.kernel.org/r/80524.1760131149@localhost [2] Reviewed-by: Hongbo Li lihongbo22@huawei.com Signed-off-by: Gao Xiang hsiangkao@linux.alibaba.com Signed-off-by: Sasha Levin sashal@kernel.org --- fs/erofs/zmap.c | 7 ++++++- 1 file changed, 6 insertions(+), 1 deletion(-)
diff --git a/fs/erofs/zmap.c b/fs/erofs/zmap.c index 798223e6da9ce..87032f90fe840 100644 --- a/fs/erofs/zmap.c +++ b/fs/erofs/zmap.c @@ -596,7 +596,7 @@ static int z_erofs_map_blocks_ext(struct inode *inode, vi->z_fragmentoff = map->m_plen; if (recsz > offsetof(struct z_erofs_extent, pstart_lo)) vi->z_fragmentoff |= map->m_pa << 32; - } else if (map->m_plen) { + } else if (map->m_plen & Z_EROFS_EXTENT_PLEN_MASK) { map->m_flags |= EROFS_MAP_MAPPED | EROFS_MAP_FULL_MAPPED | EROFS_MAP_ENCODED; fmt = map->m_plen >> Z_EROFS_EXTENT_PLEN_FMT_BIT; @@ -715,6 +715,7 @@ static int z_erofs_map_sanity_check(struct inode *inode, struct erofs_map_blocks *map) { struct erofs_sb_info *sbi = EROFS_I_SB(inode); + u64 pend;
if (!(map->m_flags & EROFS_MAP_ENCODED)) return 0; @@ -732,6 +733,10 @@ static int z_erofs_map_sanity_check(struct inode *inode, if (unlikely(map->m_plen > Z_EROFS_PCLUSTER_MAX_SIZE || map->m_llen > Z_EROFS_PCLUSTER_MAX_DSIZE)) return -EOPNOTSUPP; + /* Filesystems beyond 48-bit physical block addresses are invalid */ + if (unlikely(check_add_overflow(map->m_pa, map->m_plen, &pend) || + (pend >> sbi->blkszbits) >= BIT_ULL(48))) + return -EFSCORRUPTED; return 0; }