[PATCH 6.6 150/163] erofs: fix NULL dereference of dif->bdev_handle in fscache mode

[Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>]

6.6-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Jingbo Xu <jefflexu@xxxxxxxxxxxxxxxxx>

commit 8bd90b6ae7856dd5000b75691d905b39b9ea5d6b upstream.

Avoid NULL dereference of dif->bdev_handle, as dif->bdev_handle is NULL
in fscache mode.

 BUG: kernel NULL pointer dereference, address: 0000000000000000
 RIP: 0010:erofs_map_dev+0xbd/0x1c0
 Call Trace:
  <TASK>
  erofs_fscache_data_read_slice+0xa7/0x340
  erofs_fscache_data_read+0x11/0x30
  erofs_fscache_readahead+0xd9/0x100
  read_pages+0x47/0x1f0
  page_cache_ra_order+0x1e5/0x270
  filemap_get_pages+0xf2/0x5f0
  filemap_read+0xb8/0x2e0
  vfs_read+0x18d/0x2b0
  ksys_read+0x53/0xd0
  do_syscall_64+0x42/0xf0
  entry_SYSCALL_64_after_hwframe+0x6e/0x76

Reported-by: Yiqun Leng <yqleng@xxxxxxxxxxxxxxxxx>
Closes: https://bugzilla.openanolis.cn/show_bug.cgi?id=7245
Fixes: 49845720080d ("erofs: Convert to use bdev_open_by_path()")
Signed-off-by: Jingbo Xu <jefflexu@xxxxxxxxxxxxxxxxx>
Reviewed-by: Gao Xiang <hsiangkao@xxxxxxxxxxxxxxxxx>
Reviewed-by: Yue Hu <huyue2@xxxxxxxxxxx>
Reviewed-by: Chao Yu <chao@xxxxxxxxxx>
Link: https://lore.kernel.org/r/20231114070704.23398-1-jefflexu@xxxxxxxxxxxxxxxxx
Signed-off-by: Gao Xiang <hsiangkao@xxxxxxxxxxxxxxxxx>
Signed-off-by: Hongbo Li <lihongbo22@xxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
 fs/erofs/data.c |    5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

--- a/fs/erofs/data.c
+++ b/fs/erofs/data.c
@@ -222,7 +222,7 @@ int erofs_map_dev(struct super_block *sb
 			up_read(&devs->rwsem);
 			return 0;
 		}
-		map->m_bdev = dif->bdev_handle->bdev;
+		map->m_bdev = dif->bdev_handle ? dif->bdev_handle->bdev : NULL;
 		map->m_daxdev = dif->dax_dev;
 		map->m_dax_part_off = dif->dax_part_off;
 		map->m_fscache = dif->fscache;
@@ -240,7 +240,8 @@ int erofs_map_dev(struct super_block *sb
 			if (map->m_pa >= startoff &&
 			    map->m_pa < startoff + length) {
 				map->m_pa -= startoff;
-				map->m_bdev = dif->bdev_handle->bdev;
+				map->m_bdev = dif->bdev_handle ?
+					      dif->bdev_handle->bdev : NULL;
 				map->m_daxdev = dif->dax_dev;
 				map->m_dax_part_off = dif->dax_part_off;
 				map->m_fscache = dif->fscache;