expkey_parse() oopses when handling a 0 length export. This is easily triggerable from usermode by writing 0 bytes into '/proc/[proc id]/net/rpc/nfsd.fh/channel'. Below is the log: [ 1402.286893] BUG: unable to handle kernel paging request at ffff880077c49fff [ 1402.287632] IP: [<ffffffff812b4b99>] expkey_parse+0x28/0x2e1 [ 1402.287632] PGD 2206063 PUD 1fdfd067 PMD 1ffbc067 PTE 8000000077c49160 [ 1402.287632] Oops: 0000 [#1] PREEMPT SMP DEBUG_PAGEALLOC [ 1402.287632] CPU 1 [ 1402.287632] Pid: 20198, comm: trinity Not tainted 3.2.0-rc2-sasha-00058-gc65cd37 #6 [ 1402.287632] RIP: 0010:[<ffffffff812b4b99>] [<ffffffff812b4b99>] expkey_parse+0x28/0x2e1 [ 1402.287632] RSP: 0018:ffff880077f0fd68 EFLAGS: 00010292 [ 1402.287632] RAX: ffff880077c49fff RBX: 00000000ffffffea RCX: 0000000001043400 [ 1402.287632] RDX: 0000000000000000 RSI: ffff880077c4a000 RDI: ffffffff82283de0 [ 1402.287632] RBP: ffff880077f0fe18 R08: 0000000000000001 R09: ffff880000000000 [ 1402.287632] R10: 0000000000000000 R11: 0000000000000001 R12: ffff880077c4a000 [ 1402.287632] R13: ffffffff82283de0 R14: 0000000001043400 R15: ffffffff82283de0 [ 1402.287632] FS: 00007f25fec3f700(0000) GS:ffff88007d400000(0000) knlGS:0000000000000000 [ 1402.287632] CS: 0010 DS: 0000 ES: 0000 CR0: 000000008005003b [ 1402.287632] CR2: ffff880077c49fff CR3: 0000000077e1d000 CR4: 00000000000406e0 [ 1402.287632] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 [ 1402.287632] DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000400 [ 1402.287632] Process trinity (pid: 20198, threadinfo ffff880077f0e000, task ffff880077db17b0) [ 1402.287632] Stack: [ 1402.287632] ffff880077db17b0 ffff880077c4a000 ffff880077f0fdb8 ffffffff810b411e [ 1402.287632] ffff880000000000 ffff880077db17b0 ffff880077c4a000 ffffffff82283de0 [ 1402.287632] 0000000001043400 ffffffff82283de0 ffff880077f0fde8 ffffffff81111f63 [ 1402.287632] Call Trace: [ 1402.287632] [<ffffffff810b411e>] ? lock_release+0x1af/0x1bc [ 1402.287632] [<ffffffff81111f63>] ? might_fault+0x97/0x9e [ 1402.287632] [<ffffffff81111f1a>] ? might_fault+0x4e/0x9e [ 1402.287632] [<ffffffff81a8bcf2>] cache_do_downcall+0x3e/0x4f [ 1402.287632] [<ffffffff81a8c950>] cache_write.clone.16+0xbb/0x130 [ 1402.287632] [<ffffffff81a8c9df>] ? cache_write_pipefs+0x1a/0x1a [ 1402.287632] [<ffffffff81a8c9f8>] cache_write_procfs+0x19/0x1b [ 1402.287632] [<ffffffff8118dc54>] proc_reg_write+0x8e/0xad [ 1402.287632] [<ffffffff8113fe81>] vfs_write+0xaa/0xfd [ 1402.287632] [<ffffffff8114142d>] ? fget_light+0x35/0x9e [ 1402.287632] [<ffffffff8113ff8b>] sys_write+0x48/0x6f [ 1402.287632] [<ffffffff81bbdb92>] system_call_fastpath+0x16/0x1b [ 1402.287632] Code: c0 c9 c3 55 48 63 d2 48 89 e5 48 8d 44 32 ff 41 57 41 56 41 55 41 54 53 bb ea ff ff ff 48 81 ec 88 00 00 00 48 89 b5 58 ff ff ff [ 1402.287632] 38 0a 0f 85 89 02 00 00 c6 00 00 48 8b 3d 44 4a e5 01 48 85 [ 1402.287632] RIP [<ffffffff812b4b99>] expkey_parse+0x28/0x2e1 [ 1402.287632] RSP <ffff880077f0fd68> [ 1402.287632] CR2: ffff880077c49fff [ 1402.287632] ---[ end trace 368ef53ff773a5e3 ]--- Cc: "J. Bruce Fields" <bfields@xxxxxxxxxxxx> Cc: Neil Brown <neilb@xxxxxxx> Cc: linux-nfs@xxxxxxxxxxxxxxx Signed-off-by: Sasha Levin <levinsasha928@xxxxxxxxx> --- fs/nfsd/export.c | 2 +- 1 files changed, 1 insertions(+), 1 deletions(-) diff --git a/fs/nfsd/export.c b/fs/nfsd/export.c index 62f3b90..5f312ab 100644 --- a/fs/nfsd/export.c +++ b/fs/nfsd/export.c @@ -87,7 +87,7 @@ static int expkey_parse(struct cache_detail *cd, char *mesg, int mlen) struct svc_expkey key; struct svc_expkey *ek = NULL; - if (mesg[mlen-1] != '\n') + if (mlen < 1 || mesg[mlen-1] != '\n') return -EINVAL; mesg[mlen-1] = 0; -- 1.7.8.rc1 -- 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
