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tmpfs,ceph,gfs2,isofs,reiserfs,xfs: fix fh_len checking

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Fuzzing with trinity oopsed on the 1st instruction of shmem_fh_to_dentry(),
	u64 inum = fid->raw[2];
which is unhelpfully reported as at the end of shmem_alloc_inode():

BUG: unable to handle kernel paging request at ffff880061cd3000
IP: [<ffffffff812190d0>] shmem_alloc_inode+0x40/0x40
Oops: 0000 [#1] PREEMPT SMP DEBUG_PAGEALLOC
Call Trace:
 [<ffffffff81488649>] ? exportfs_decode_fh+0x79/0x2d0
 [<ffffffff812d77c3>] do_handle_open+0x163/0x2c0
 [<ffffffff812d792c>] sys_open_by_handle_at+0xc/0x10
 [<ffffffff83a5f3f8>] tracesys+0xe1/0xe6

Right, tmpfs is being stupid to access fid->raw[2] before validating that
fh_len includes it: the buffer kmalloc'ed by do_sys_name_to_handle() may
fall at the end of a page, and the next page not be present.

But some other filesystems (ceph, gfs2, isofs, reiserfs, xfs) are being
careless about fh_len too, in fh_to_dentry() and/or fh_to_parent(), and
could oops in the same way: add the missing fh_len checks to those.

Reported-by: Sasha Levin <[email protected]>
Signed-off-by: Hugh Dickins <[email protected]>
Cc: Al Viro <[email protected]>
Cc: Sage Weil <[email protected]>
Cc: Steven Whitehouse <[email protected]>
Cc: Christoph Hellwig <[email protected]>
Cc: [email protected]
Signed-off-by: Al Viro <[email protected]>
This commit is contained in:
Hugh Dickins 2012-10-07 20:32:51 -07:00 • committed by Al Viro
commit 35c2a7f490
6 changed files with 31 additions and 8 deletions
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4
fs/gfs2/export.c
View file

@ -161,6 +161,8 @@ static struct dentry *gfs2_fh_to_dentry(struct super_block *sb, struct fid *fid,
case GFS2_SMALL_FH_SIZE:
case GFS2_LARGE_FH_SIZE:
case GFS2_OLD_FH_SIZE:
if (fh_len < GFS2_SMALL_FH_SIZE)
return NULL;
this.no_formal_ino = ((u64)be32_to_cpu(fh[0])) << 32;
this.no_formal_ino |= be32_to_cpu(fh[1]);
this.no_addr = ((u64)be32_to_cpu(fh[2])) << 32;
@ -180,6 +182,8 @@ static struct dentry *gfs2_fh_to_parent(struct super_block *sb, struct fid *fid,
switch (fh_type) {
case GFS2_LARGE_FH_SIZE:
case GFS2_OLD_FH_SIZE:
if (fh_len < GFS2_LARGE_FH_SIZE)
return NULL;
parent.no_formal_ino = ((u64)be32_to_cpu(fh[4])) << 32;
parent.no_formal_ino |= be32_to_cpu(fh[5]);
parent.no_addr = ((u64)be32_to_cpu(fh[6])) << 32;