diff mbox series

[bpf-next,1/2] bpf: Avoid dummy bpf_offload_netdev in __bpf_prog_dev_bound_init

Message ID 20230912005539.2248244-2-eddyz87@gmail.com (mailing list archive)
State Accepted
Commit 1a49f4195d3498fe458a7f5ff7ec5385da70d92e
Delegated to: BPF
Headers show
Series Avoid dummy bpf_offload_netdev in __bpf_prog_dev_bound_init | expand

Checks

Context Check Description
bpf/vmtest-bpf-next-PR success PR summary
netdev/series_format success Posting correctly formatted
netdev/tree_selection success Clearly marked for bpf-next
netdev/fixes_present success Fixes tag not required for -next series
netdev/header_inline success No static functions without inline keyword in header files
netdev/build_32bit success Errors and warnings before: 1342 this patch: 1342
netdev/cc_maintainers warning 5 maintainers not CCed: jolsa@kernel.org haoluo@google.com john.fastabend@gmail.com kpsingh@kernel.org song@kernel.org
netdev/build_clang success Errors and warnings before: 1364 this patch: 1364
netdev/verify_signedoff success Signed-off-by tag matches author and committer
netdev/deprecated_api success None detected
netdev/check_selftest success No net selftest shell script
netdev/verify_fixes success Fixes tag looks correct
netdev/build_allmodconfig_warn success Errors and warnings before: 1365 this patch: 1365
netdev/checkpatch success total: 0 errors, 0 warnings, 0 checks, 19 lines checked
netdev/kdoc success Errors and warnings before: 0 this patch: 0
netdev/source_inline success Was 0 now: 0
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bpf/vmtest-bpf-next-VM_Test-13 fail Logs for test_progs on x86_64 with llvm-16
bpf/vmtest-bpf-next-VM_Test-17 fail Logs for test_progs_no_alu32 on x86_64 with llvm-16
bpf/vmtest-bpf-next-VM_Test-16 fail Logs for test_progs_no_alu32 on x86_64 with gcc
bpf/vmtest-bpf-next-VM_Test-25 success Logs for test_verifier on s390x with gcc
bpf/vmtest-bpf-next-VM_Test-14 fail Logs for test_progs_no_alu32 on aarch64 with gcc
bpf/vmtest-bpf-next-VM_Test-15 fail Logs for test_progs_no_alu32 on s390x with gcc
bpf/vmtest-bpf-next-VM_Test-11 fail Logs for test_progs on s390x with gcc
bpf/vmtest-bpf-next-VM_Test-7 success Logs for test_maps on s390x with gcc
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Commit Message

Eduard Zingerman Sept. 12, 2023, 12:55 a.m. UTC 
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>
---
 kernel/bpf/offload.c | 12 +++++++-----
 1 file changed, 7 insertions(+), 5 deletions(-)
diff mbox series

Patch

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.
 		 */