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 > -- 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
