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authorDominique Martinet <dominique.martinet@cea.fr>2018-11-05 09:52:48 +0100
committerDominique Martinet <dominique.martinet@cea.fr>2018-12-25 17:07:49 +0900
commit574d356b7a02c7e1b01a1d9cba8a26b3c2888f45 (patch)
tree58624999ebadfabc02b63ee7f875cfe0fcadbf64 /net
parent52ad259eaac0454c1ac7123e7148cf8d6e6f5301 (diff)
9p/net: put a lower bound on msize
If the requested msize is too small (either from command line argument or from the server version reply), we won't get any work done. If it's *really* too small, nothing will work, and this got caught by syzbot recently (on a new kmem_cache_create_usercopy() call) Just set a minimum msize to 4k in both code paths, until someone complains they have a use-case for a smaller msize. We need to check in both mount option and server reply individually because the msize for the first version request would be unchecked with just a global check on clnt->msize. Link: http://lkml.kernel.org/r/1541407968-31350-1-git-send-email-asmadeus@codewreck.org Reported-by: syzbot+0c1d61e4db7db94102ca@syzkaller.appspotmail.com Signed-off-by: Dominique Martinet <dominique.martinet@cea.fr> Cc: Eric Van Hensbergen <ericvh@gmail.com> Cc: Latchesar Ionkov <lucho@ionkov.net> Cc: stable@vger.kernel.org
Diffstat (limited to 'net')
-rw-r--r--net/9p/client.c21
1 files changed, 21 insertions, 0 deletions
diff --git a/net/9p/client.c b/net/9p/client.c
index 2c9a17b9b46b..357214a51f13 100644
--- a/net/9p/client.c
+++ b/net/9p/client.c
@@ -181,6 +181,12 @@ static int parse_opts(char *opts, struct p9_client *clnt)
ret = r;
continue;
}
+ if (option < 4096) {
+ p9_debug(P9_DEBUG_ERROR,
+ "msize should be at least 4k\n");
+ ret = -EINVAL;
+ continue;
+ }
clnt->msize = option;
break;
case Opt_trans:
@@ -983,10 +989,18 @@ static int p9_client_version(struct p9_client *c)
else if (!strncmp(version, "9P2000", 6))
c->proto_version = p9_proto_legacy;
else {
+ p9_debug(P9_DEBUG_ERROR,
+ "server returned an unknown version: %s\n", version);
err = -EREMOTEIO;
goto error;
}
+ if (msize < 4096) {
+ p9_debug(P9_DEBUG_ERROR,
+ "server returned a msize < 4096: %d\n", msize);
+ err = -EREMOTEIO;
+ goto error;
+ }
if (msize < c->msize)
c->msize = msize;
@@ -1043,6 +1057,13 @@ struct p9_client *p9_client_create(const char *dev_name, char *options)
if (clnt->msize > clnt->trans_mod->maxsize)
clnt->msize = clnt->trans_mod->maxsize;
+ if (clnt->msize < 4096) {
+ p9_debug(P9_DEBUG_ERROR,
+ "Please specify a msize of at least 4k\n");
+ err = -EINVAL;
+ goto free_client;
+ }
+
err = p9_client_version(clnt);
if (err)
goto close_trans;

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