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author | Harshula Jayasuriya <harshula@redhat.com> | 2013-07-23 04:21:35 (GMT) |
---|---|---|
committer | J. Bruce Fields <bfields@redhat.com> | 2013-07-23 16:15:32 (GMT) |
commit | e4daf1ffbe6cc3b12aab4d604e627829e93e9914 (patch) | |
tree | b3279011fb0a21f5e801b3b81e884a0b69aa3727 /fs | |
parent | 3b2f64d00c46e1e4e9bd0bb9bb12619adac27a4b (diff) | |
download | linux-fsl-qoriq-e4daf1ffbe6cc3b12aab4d604e627829e93e9914.tar.xz |
nfsd: nfsd_open: when dentry_open returns an error do not propagate as struct file
The following call chain:
------------------------------------------------------------
nfs4_get_vfs_file
- nfsd_open
- dentry_open
- do_dentry_open
- __get_file_write_access
- get_write_access
- return atomic_inc_unless_negative(&inode->i_writecount) ? 0 : -ETXTBSY;
------------------------------------------------------------
can result in the following state:
------------------------------------------------------------
struct nfs4_file {
...
fi_fds = {0xffff880c1fa65c80, 0xffffffffffffffe6, 0x0},
fi_access = {{
counter = 0x1
}, {
counter = 0x0
}},
...
------------------------------------------------------------
1) First time around, in nfs4_get_vfs_file() fp->fi_fds[O_WRONLY] is
NULL, hence nfsd_open() is called where we get status set to an error
and fp->fi_fds[O_WRONLY] to -ETXTBSY. Thus we do not reach
nfs4_file_get_access() and fi_access[O_WRONLY] is not incremented.
2) Second time around, in nfs4_get_vfs_file() fp->fi_fds[O_WRONLY] is
NOT NULL (-ETXTBSY), so nfsd_open() is NOT called, but
nfs4_file_get_access() IS called and fi_access[O_WRONLY] is incremented.
Thus we leave a landmine in the form of the nfs4_file data structure in
an incorrect state.
3) Eventually, when __nfs4_file_put_access() is called it finds
fi_access[O_WRONLY] being non-zero, it decrements it and calls
nfs4_file_put_fd() which tries to fput -ETXTBSY.
------------------------------------------------------------
...
[exception RIP: fput+0x9]
RIP: ffffffff81177fa9 RSP: ffff88062e365c90 RFLAGS: 00010282
RAX: ffff880c2b3d99cc RBX: ffff880c2b3d9978 RCX: 0000000000000002
RDX: dead000000100101 RSI: 0000000000000001 RDI: ffffffffffffffe6
RBP: ffff88062e365c90 R8: ffff88041fe797d8 R9: ffff88062e365d58
R10: 0000000000000008 R11: 0000000000000000 R12: 0000000000000001
R13: 0000000000000007 R14: 0000000000000000 R15: 0000000000000000
ORIG_RAX: ffffffffffffffff CS: 0010 SS: 0018
#9 [ffff88062e365c98] __nfs4_file_put_access at ffffffffa0562334 [nfsd]
#10 [ffff88062e365cc8] nfs4_file_put_access at ffffffffa05623ab [nfsd]
#11 [ffff88062e365ce8] free_generic_stateid at ffffffffa056634d [nfsd]
#12 [ffff88062e365d18] release_open_stateid at ffffffffa0566e4b [nfsd]
#13 [ffff88062e365d38] nfsd4_close at ffffffffa0567401 [nfsd]
#14 [ffff88062e365d88] nfsd4_proc_compound at ffffffffa0557f28 [nfsd]
#15 [ffff88062e365dd8] nfsd_dispatch at ffffffffa054543e [nfsd]
#16 [ffff88062e365e18] svc_process_common at ffffffffa04ba5a4 [sunrpc]
#17 [ffff88062e365e98] svc_process at ffffffffa04babe0 [sunrpc]
#18 [ffff88062e365eb8] nfsd at ffffffffa0545b62 [nfsd]
#19 [ffff88062e365ee8] kthread at ffffffff81090886
#20 [ffff88062e365f48] kernel_thread at ffffffff8100c14a
------------------------------------------------------------
Cc: stable@vger.kernel.org
Signed-off-by: Harshula Jayasuriya <harshula@redhat.com>
Signed-off-by: J. Bruce Fields <bfields@redhat.com>
Diffstat (limited to 'fs')
-rw-r--r-- | fs/nfsd/vfs.c | 5 |
1 files changed, 3 insertions, 2 deletions
diff --git a/fs/nfsd/vfs.c b/fs/nfsd/vfs.c index 8ff6a00..c827acb 100644 --- a/fs/nfsd/vfs.c +++ b/fs/nfsd/vfs.c @@ -830,9 +830,10 @@ nfsd_open(struct svc_rqst *rqstp, struct svc_fh *fhp, umode_t type, flags = O_WRONLY|O_LARGEFILE; } *filp = dentry_open(&path, flags, current_cred()); - if (IS_ERR(*filp)) + if (IS_ERR(*filp)) { host_err = PTR_ERR(*filp); - else { + *filp = NULL; + } else { host_err = ima_file_check(*filp, may_flags); if (may_flags & NFSD_MAY_64BIT_COOKIE) |