| Message ID | 1375112056-3211-1-git-send-email-luis.henriques@canonical.com |
|---|---|
| State | New |
| Headers | show |
diff --git a/fs/nfsd/vfs.c b/fs/nfsd/vfs.c index 0191ede..20c5092 100644 --- a/fs/nfsd/vfs.c +++ b/fs/nfsd/vfs.c @@ -794,9 +794,10 @@ nfsd_open(struct svc_rqst *rqstp, struct svc_fh *fhp, umode_t type, } *filp = dentry_open(dget(dentry), mntget(fhp->fh_export->ex_path.mnt), 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)
This is a note to let you know that I have just added a patch titled nfsd: nfsd_open: when dentry_open returns an error do not to the linux-3.5.y-queue branch of the 3.5.y.z extended stable tree which can be found at: http://kernel.ubuntu.com/git?p=ubuntu/linux.git;a=shortlog;h=refs/heads/linux-3.5.y-queue If you, or anyone else, feels it should not be added to this tree, please reply to this email. For more information about the 3.5.y.z tree, see https://wiki.ubuntu.com/Kernel/Dev/ExtendedStable Thanks. -Luis ------ From f085b838f2ebb0429f381be9ec84420480e831f6 Mon Sep 17 00:00:00 2001 From: Harshula Jayasuriya <harshula@redhat.com> Date: Tue, 23 Jul 2013 14:21:35 +1000 Subject: [PATCH] nfsd: nfsd_open: when dentry_open returns an error do not propagate as struct file commit e4daf1ffbe6cc3b12aab4d604e627829e93e9914 upstream. 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 ------------------------------------------------------------ Signed-off-by: Harshula Jayasuriya <harshula@redhat.com> Signed-off-by: J. Bruce Fields <bfields@redhat.com> [ luis: backported to 3.5: adjusted context ] Signed-off-by: Luis Henriques <luis.henriques@canonical.com> --- fs/nfsd/vfs.c | 5 +++-- 1 file changed, 3 insertions(+), 2 deletions(-) -- 1.8.1.2