| Message ID | 1541407968-31350-1-git-send-email-asmadeus@codewreck.org |
|---|---|
| State | Not Applicable, archived |
| Delegated to: | David Miller |
| Headers | show |
| Series | 9p/net: put a lower bound on msize | expand |
Dominique Martinet wrote on Mon, Nov 05, 2018: > From: Dominique Martinet <dominique.martinet@cea.fr> > > 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. > > 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> > --- > net/9p/client.c | 21 +++++++++++++++++++++ > 1 file changed, 21 insertions(+) > > diff --git a/net/9p/client.c b/net/9p/client.c > index 2c9a17b9b46b..b1163ebdc622 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 (r < 4096) { This should read if (option < 4096), amending what I've put in for -next last week :( Reviews wanted! > + 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;
diff --git a/net/9p/client.c b/net/9p/client.c index 2c9a17b9b46b..b1163ebdc622 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 (r < 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;