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authorEduard Zingerman <eddyz87@gmail.com>2023-09-12 03:55:37 +0300
committerMartin KaFai Lau <martin.lau@kernel.org>2023-09-12 08:06:06 +0300
commit1a49f4195d3498fe458a7f5ff7ec5385da70d92e (patch)
treeaf192f1718f0ecc30b641990d98ac6c2182e8e96 /kernel
parenta34a9f1a19afe9c60ca0ea61dfeee63a1c2baac8 (diff)
downloadlinux-1a49f4195d3498fe458a7f5ff7ec5385da70d92e.tar.xz
bpf: Avoid dummy bpf_offload_netdev in __bpf_prog_dev_bound_init
Fix for a bug observable under the following sequence of events: 1. Create a network device that does not support XDP offload. 2. Load a device bound XDP program with BPF_F_XDP_DEV_BOUND_ONLY flag (such programs are not offloaded). 3. Load a device bound XDP program with zero flags (such programs are offloaded). At step (2) __bpf_prog_dev_bound_init() associates with device (1) a dummy bpf_offload_netdev struct with .offdev field set to NULL. At step (3) __bpf_prog_dev_bound_init() would reuse dummy struct allocated at step (2). However, downstream usage of the bpf_offload_netdev assumes that .offdev field can't be NULL, e.g. in bpf_prog_offload_verifier_prep(). Adjust __bpf_prog_dev_bound_init() to require bpf_offload_netdev with non-NULL .offdev for offloaded BPF programs. Fixes: 2b3486bc2d23 ("bpf: Introduce device-bound XDP programs") Reported-by: syzbot+291100dcb32190ec02a8@syzkaller.appspotmail.com Closes: https://lore.kernel.org/bpf/000000000000d97f3c060479c4f8@google.com/ Signed-off-by: Eduard Zingerman <eddyz87@gmail.com> Link: https://lore.kernel.org/r/20230912005539.2248244-2-eddyz87@gmail.com Signed-off-by: Martin KaFai Lau <martin.lau@kernel.org>
Diffstat (limited to 'kernel')
-rw-r--r--kernel/bpf/offload.c12
1 files changed, 7 insertions, 5 deletions
diff --git a/kernel/bpf/offload.c b/kernel/bpf/offload.c
index 3e4f2ec1af06..87d6693d8233 100644
--- a/kernel/bpf/offload.c
+++ b/kernel/bpf/offload.c
@@ -199,12 +199,14 @@ static int __bpf_prog_dev_bound_init(struct bpf_prog *prog, struct net_device *n
offload->netdev = netdev;
ondev = bpf_offload_find_netdev(offload->netdev);
+ /* When program is offloaded require presence of "true"
+ * bpf_offload_netdev, avoid the one created for !ondev case below.
+ */
+ if (bpf_prog_is_offloaded(prog->aux) && (!ondev || !ondev->offdev)) {
+ err = -EINVAL;
+ goto err_free;
+ }
if (!ondev) {
- if (bpf_prog_is_offloaded(prog->aux)) {
- err = -EINVAL;
- goto err_free;
- }
-
/* When only binding to the device, explicitly
* create an entry in the hashtable.
*/