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authorSiddh Raman Pant <code@siddh.me>2023-06-20 19:47:00 +0300
committerDave Kleikamp <dave.kleikamp@oracle.com>2023-06-20 20:37:50 +0300
commit11509910c599cbd04585ec35a6d5e1a0053d84c1 (patch)
tree76343f909d266e603c784eed0336a0594d10e5f1 /fs/jfs
parent692b7dc87ca6d55ab254f8259e6f970171dc9d01 (diff)
downloadlinux-11509910c599cbd04585ec35a6d5e1a0053d84c1.tar.xz
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.c6
-rw-r--r--fs/jfs/jfs_filsys.h2
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