From 43def35c1030d91a7414936c7c1b416828b20afb Mon Sep 17 00:00:00 2001 From: Simon Derr Date: Fri, 10 Aug 2012 15:52:06 +0200 Subject: [PATCH] net/9p: Check errno validity While working on a modified server I had the Linux clients crash a few times. This lead me to find this: Some error codes are directly extracted from the server replies. A malformed server reply could contain an invalid error code, with a very large value. If this value is then passed to ERR_PTR() it will not be properly detected as an error code by IS_ERR() and as a result the kernel will dereference an invalid pointer. This patch tries to avoid this. Signed-off-by: Simon Derr Signed-off-by: Eric Van Hensbergen --- net/9p/client.c | 18 ++++++++++++++++-- 1 file changed, 16 insertions(+), 2 deletions(-) diff --git a/net/9p/client.c b/net/9p/client.c index 8260f132b32..34d41767093 100644 --- a/net/9p/client.c +++ b/net/9p/client.c @@ -76,6 +76,20 @@ inline int p9_is_proto_dotu(struct p9_client *clnt) } EXPORT_SYMBOL(p9_is_proto_dotu); +/* + * Some error codes are taken directly from the server replies, + * make sure they are valid. + */ +static int safe_errno(int err) +{ + if ((err > 0) || (err < -MAX_ERRNO)) { + p9_debug(P9_DEBUG_ERROR, "Invalid error code %d\n", err); + return -EPROTO; + } + return err; +} + + /* Interpret mount option for protocol version */ static int get_protocol_version(char *s) { @@ -782,7 +796,7 @@ again: return req; reterr: p9_free_req(c, req); - return ERR_PTR(err); + return ERR_PTR(safe_errno(err)); } /** @@ -865,7 +879,7 @@ static struct p9_req_t *p9_client_zc_rpc(struct p9_client *c, int8_t type, return req; reterr: p9_free_req(c, req); - return ERR_PTR(err); + return ERR_PTR(safe_errno(err)); } static struct p9_fid *p9_fid_create(struct p9_client *clnt)