diff options
| author | Siddh Raman Pant <code@siddh.me> | 2023-06-20 22:17:00 +0530 |
|---|---|---|
| committer | Dave Kleikamp <dave.kleikamp@oracle.com> | 2023-06-20 12:37:50 -0500 |
| commit | 11509910c599cbd04585ec35a6d5e1a0053d84c1 (patch) | |
| tree | 76343f909d266e603c784eed0336a0594d10e5f1 /fs/jfs | |
| parent | 692b7dc87ca6d55ab254f8259e6f970171dc9d01 (diff) | |
| download | lwn-11509910c599cbd04585ec35a6d5e1a0053d84c1.tar.gz lwn-11509910c599cbd04585ec35a6d5e1a0053d84c1.zip | |
jfs: jfs_dmap: Validate db_l2nbperpage while mounting
In jfs_dmap.c at line 381, BLKTODMAP is used to get a logical block
number inside dbFree(). db_l2nbperpage, which is the log2 number of
blocks per page, is passed as an argument to BLKTODMAP which uses it
for shifting.
Syzbot reported a shift out-of-bounds crash because db_l2nbperpage is
too big. This happens because the large value is set without any
validation in dbMount() at line 181.
Thus, make sure that db_l2nbperpage is correct while mounting.
Max number of blocks per page = Page size / Min block size
=> log2(Max num_block per page) = log2(Page size / Min block size)
= log2(Page size) - log2(Min block size)
=> Max db_l2nbperpage = L2PSIZE - L2MINBLOCKSIZE
Reported-and-tested-by: syzbot+d2cd27dcf8e04b232eb2@syzkaller.appspotmail.com
Closes: https://syzkaller.appspot.com/bug?id=2a70a453331db32ed491f5cbb07e81bf2d225715
Cc: stable@vger.kernel.org
Suggested-by: Dave Kleikamp <dave.kleikamp@oracle.com>
Signed-off-by: Siddh Raman Pant <code@siddh.me>
Signed-off-by: Dave Kleikamp <dave.kleikamp@oracle.com>
Diffstat (limited to 'fs/jfs')
| -rw-r--r-- | fs/jfs/jfs_dmap.c | 6 | ||||
| -rw-r--r-- | fs/jfs/jfs_filsys.h | 2 |
2 files changed, 8 insertions, 0 deletions
diff --git a/fs/jfs/jfs_dmap.c b/fs/jfs/jfs_dmap.c index a3eb1e826947..da6a2bc6bf02 100644 --- a/fs/jfs/jfs_dmap.c +++ b/fs/jfs/jfs_dmap.c @@ -178,7 +178,13 @@ int dbMount(struct inode *ipbmap) dbmp_le = (struct dbmap_disk *) mp->data; bmp->db_mapsize = le64_to_cpu(dbmp_le->dn_mapsize); bmp->db_nfree = le64_to_cpu(dbmp_le->dn_nfree); + bmp->db_l2nbperpage = le32_to_cpu(dbmp_le->dn_l2nbperpage); + if (bmp->db_l2nbperpage > L2PSIZE - L2MINBLOCKSIZE) { + err = -EINVAL; + goto err_release_metapage; + } + bmp->db_numag = le32_to_cpu(dbmp_le->dn_numag); if (!bmp->db_numag) { err = -EINVAL; diff --git a/fs/jfs/jfs_filsys.h b/fs/jfs/jfs_filsys.h index b5d702df7111..33ef13a0b110 100644 --- a/fs/jfs/jfs_filsys.h +++ b/fs/jfs/jfs_filsys.h @@ -122,7 +122,9 @@ #define NUM_INODE_PER_IAG INOSPERIAG #define MINBLOCKSIZE 512 +#define L2MINBLOCKSIZE 9 #define MAXBLOCKSIZE 4096 +#define L2MAXBLOCKSIZE 12 #define MAXFILESIZE ((s64)1 << 52) #define JFS_LINK_MAX 0xffffffff |