On Mon, 19 Jan 2015 09:17:51 +0800 Junxiao Bi <junxiao.bi@xxxxxxxxxx> wrote: > On 01/18/2015 10:43 PM, Trond Myklebust wrote: > > On Sun, Jan 18, 2015 at 7:29 AM, Junxiao Bi <junxiao.bi@xxxxxxxxxx> wrote: > >> > >> nfsd4_decode_open() doesn't initialize variable open->op_file and > >> open->op_stp, they are initialized in nfsd4_process_open1(), but if > >> any error happens before initializing them, nfsd4_open() will call > >> into nfsd4_cleanup_open_state() and corrupt the memory. > >> > >> Since nfsd4_process_open1() will initialize these two variables and > >> open->op_openowner, make them default to null at the beginning. > >> > >> Signed-off-by: Junxiao Bi <junxiao.bi@xxxxxxxxxx> > >> --- > >> fs/nfsd/nfs4state.c | 4 ++++ > >> 1 file changed, 4 insertions(+) > >> > >> diff --git a/fs/nfsd/nfs4state.c b/fs/nfsd/nfs4state.c > >> index c06a1ba..6e74a91 100644 > >> --- a/fs/nfsd/nfs4state.c > >> +++ b/fs/nfsd/nfs4state.c > >> @@ -3547,6 +3547,10 @@ nfsd4_process_open1(struct nfsd4_compound_state *cstate, > >> struct nfs4_openowner *oo = NULL; > >> __be32 status; > >> > >> + open->op_file = NULL; > >> + open->op_openowner = NULL; > >> + open->op_stp = NULL; > >> + > >> if (STALE_CLIENTID(&open->op_clientid, nn)) > >> return nfserr_stale_clientid; > >> /* > > > > Have you ever seen an instance of this corruption? I would have > > thought that the kzalloc() in nfsd4_decode_compound() and/or the > > earlier memset() in svc_process_common() would ensure that these > > fields are always initialised to NULL. > Yes, we got the following panic from 3.8.13. The bad pointer > open->op_stp was freed into kmem_cache array_cache, and was allocated to > next "op_stp" allocation request which triggered the panic. > > > @ PID: 21663 TASK: ffff8809fe6103c0 CPU: 0 COMMAND: "nfsd" > @ #0 [ffff8809fe613980] machine_kexec at ffffffff810421d9 > @ #1 [ffff8809fe6139f0] crash_kexec at ffffffff810c9d39 > @ #2 [ffff8809fe613ac0] oops_end at ffffffff81599298 > @ #3 [ffff8809fe613af0] die at ffffffff8101870b > @ #4 [ffff8809fe613b20] do_general_protection at ffffffff8159906c > @ #5 [ffff8809fe613b50] general_protection at ffffffff81598668 > @ [exception RIP: init_stid+14] > @ RIP: ffffffffa058247e RSP: ffff8809fe613c08 RFLAGS: 00010292 > @ RAX: 0000000000000000 RBX: 736e61727465722c RCX: 0000000000000000 > @ RDX: 0000000000000001 RSI: ffff8808e433a800 RDI: 736e61727465722c > @ RBP: ffff8809fe613c28 R8: ffff880a01469000 R9: 0000000000000000 > @ R10: 0000000000000000 R11: 0000000000000000 R12: ffff8808e19821a0 > @ R13: ffff8809aa40f3a8 R14: ffff8809fd781040 R15: ffff8809aafc9c98 > @ ORIG_RAX: ffffffffffffffff CS: 0010 SS: 0018 > @ #6 [ffff8809fe613c30] nfsd4_process_open2 at ffffffffa0588123 [nfsd] > @ #7 [ffff8809fe613d00] nfsd4_open at ffffffffa0577e82 [nfsd] > @ #8 [ffff8809fe613d50] nfsd4_proc_compound at ffffffffa0575de8 [nfsd] > @ #9 [ffff8809fe613db0] nfsd_dispatch at ffffffffa056429b [nfsd] > @ #10 [ffff8809fe613df0] svc_process_common at ffffffffa04afd14 [sunrpc] > @ #11 [ffff8809fe613e70] svc_process at ffffffffa04b034f [sunrpc] > @ #12 [ffff8809fe613e90] nfsd at ffffffffa05649ff [nfsd] > @ #13 [ffff8809fe613ec0] kthread at ffffffff81082f4e > @ #14 [ffff8809fe613f50] ret_from_fork at ffffffff815a09ac > > Thanks, > Junxiao. > > > > > Cheers > > Trond > > > I agree with Trond. This patch doesn't make much sense. Why isn't that memset in svc_process_common() zeroing this out? If this is a bug in the open codepath, then it's almost certainly a bug for other compound ops. I'd suggest doing a bit more investigative work and see if you can figure out why that isn't working as expected... -- Jeff Layton <jlayton@xxxxxxxxxxxxxxx> -- To unsubscribe from this list: send the line "unsubscribe linux-nfs" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
