Patch "gtp: allow -1 to be specified as file description from userspace" has been added to the 5.4-stable tree

[Sasha Levin <sashal@xxxxxxxxxx>]

This is a note to let you know that I've just added the patch titled

    gtp: allow -1 to be specified as file description from userspace

to the 5.4-stable tree which can be found at:
    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     gtp-allow-1-to-be-specified-as-file-description-from.patch
and it can be found in the queue-5.4 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.



commit d4a08e3d599fb56118de27499d2c6a4e0815e920
Author: Pablo Neira Ayuso <pablo@xxxxxxxxxxxxx>
Date:   Tue Oct 22 16:48:25 2024 +0200

    gtp: allow -1 to be specified as file description from userspace
    
    [ Upstream commit 7515e37bce5c428a56a9b04ea7e96b3f53f17150 ]
    
    Existing user space applications maintained by the Osmocom project are
    breaking since a recent fix that addresses incorrect error checking.
    
    Restore operation for user space programs that specify -1 as file
    descriptor to skip GTPv0 or GTPv1 only sockets.
    
    Fixes: defd8b3c37b0 ("gtp: fix a potential NULL pointer dereference")
    Reported-by: Pau Espin Pedrol <pespin@xxxxxxxxxxx>
    Signed-off-by: Pablo Neira Ayuso <pablo@xxxxxxxxxxxxx>
    Tested-by: Oliver Smith <osmith@xxxxxxxxxxx>
    Reviewed-by: Simon Horman <horms@xxxxxxxxxx>
    Link: https://patch.msgid.link/20241022144825.66740-1-pablo@xxxxxxxxxxxxx
    Signed-off-by: Jakub Kicinski <kuba@xxxxxxxxxx>
    Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>

diff --git a/drivers/net/gtp.c b/drivers/net/gtp.c
index 9c62bc277ae86..f85f4e3d28215 100644
--- a/drivers/net/gtp.c
+++ b/drivers/net/gtp.c
@@ -848,20 +848,24 @@ static int gtp_encap_enable(struct gtp_dev *gtp, struct nlattr *data[])
 	unsigned int role = GTP_ROLE_GGSN;
 
 	if (data[IFLA_GTP_FD0]) {
-		u32 fd0 = nla_get_u32(data[IFLA_GTP_FD0]);
+		int fd0 = nla_get_u32(data[IFLA_GTP_FD0]);
 
-		sk0 = gtp_encap_enable_socket(fd0, UDP_ENCAP_GTP0, gtp);
-		if (IS_ERR(sk0))
-			return PTR_ERR(sk0);
+		if (fd0 >= 0) {
+			sk0 = gtp_encap_enable_socket(fd0, UDP_ENCAP_GTP0, gtp);
+			if (IS_ERR(sk0))
+				return PTR_ERR(sk0);
+		}
 	}
 
 	if (data[IFLA_GTP_FD1]) {
-		u32 fd1 = nla_get_u32(data[IFLA_GTP_FD1]);
+		int fd1 = nla_get_u32(data[IFLA_GTP_FD1]);
 
-		sk1u = gtp_encap_enable_socket(fd1, UDP_ENCAP_GTP1U, gtp);
-		if (IS_ERR(sk1u)) {
-			gtp_encap_disable_sock(sk0);
-			return PTR_ERR(sk1u);
+		if (fd1 >= 0) {
+			sk1u = gtp_encap_enable_socket(fd1, UDP_ENCAP_GTP1U, gtp);
+			if (IS_ERR(sk1u)) {
+				gtp_encap_disable_sock(sk0);
+				return PTR_ERR(sk1u);
+			}
 		}
 	}