| Message ID | 1374553295.5454.92.camel@serendib (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
Thanks, applying for 3.11.--b. On Tue, Jul 23, 2013 at 02:21:35PM +1000, Harshula Jayasuriya wrote: > 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> > --- > fs/nfsd/vfs.c | 5 +++-- > 1 file 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) > -- > 1.8.1.4 > -- To unsubscribe from this list: send the line "unsubscribe linux-nfs" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
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)
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> --- fs/nfsd/vfs.c | 5 +++-- 1 file changed, 3 insertions(+), 2 deletions(-)