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SUNRPC: Replace strlcpy() with strscpy()

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strlcpy() reads the entire source buffer first. This read may exceed
the destination size limit. This is both inefficient and can lead
to linear read overflows if a source string is not NUL-terminated[1].
Additionally, it returns the size of the source string, not the
resulting size of the destination string. In an effort to remove strlcpy()
completely[2], replace strlcpy() here with strscpy().

Explicitly handle the truncation case by returning the size of the
resulting string.

If "nodename" was ever longer than sizeof(clnt->cl_nodename) - 1, this
change will fix a bug where clnt->cl_nodelen would end up thinking there
were more characters in clnt->cl_nodename than there actually were,
which might have lead to kernel memory content exposures.

Cc: Trond Myklebust <trond.myklebust@hammerspace.com>
Cc: Anna Schumaker <anna@kernel.org>
Cc: Chuck Lever <chuck.lever@oracle.com>
Cc: Jeff Layton <jlayton@kernel.org>
Cc: Neil Brown <neilb@suse.de>
Cc: Olga Kornievskaia <kolga@netapp.com>
Cc: Dai Ngo <Dai.Ngo@oracle.com>
Cc: Tom Talpey <tom@talpey.com>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: Eric Dumazet <edumazet@google.com>
Cc: Jakub Kicinski <kuba@kernel.org>
Cc: Paolo Abeni <pabeni@redhat.com>
Cc: linux-nfs@vger.kernel.org
Cc: netdev@vger.kernel.org
Link: https://www.kernel.org/doc/html/latest/process/deprecated.html#strlcpy [1]
Link: https://github.com/KSPP/linux/issues/89 [2]
Co-developed-by: Azeem Shaikh <azeemshaikh38@gmail.com>
Signed-off-by: Azeem Shaikh <azeemshaikh38@gmail.com>
Reviewed-by: NeilBrown <neilb@suse.de>
Link: https://lore.kernel.org/r/20231114175407.work.410-kees@kernel.org
Signed-off-by: Kees Cook <keescook@chromium.org>
This commit is contained in:
Kees Cook 2023-11-14 09:54:18 -08:00
parent 98b1cc82c4
commit cb6d2fd30d
1 changed files with 8 additions and 2 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

10
net/sunrpc/clnt.c
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@ -287,8 +287,14 @@ static struct rpc_xprt *rpc_clnt_set_transport(struct rpc_clnt *clnt,
static void rpc_clnt_set_nodename(struct rpc_clnt *clnt, const char *nodename)
{
clnt->cl_nodelen = strlcpy(clnt->cl_nodename,
nodename, sizeof(clnt->cl_nodename));
ssize_t copied;
copied = strscpy(clnt->cl_nodename,
nodename, sizeof(clnt->cl_nodename));
clnt->cl_nodelen = copied < 0
? sizeof(clnt->cl_nodename) - 1
: copied;
}
static int rpc_client_register(struct rpc_clnt *clnt,