FAILED: patch "[PATCH] bpf: Fix use-after-free in bpf_uprobe_multi_link_attach()" failed to apply to 6.11-stable tree

The patch below does not apply to the 6.11-stable tree.
If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to <[email protected]>.

To reproduce the conflict and resubmit, you may use the following commands:

git fetch https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/ linux-6.11.y
git checkout FETCH_HEAD
git cherry-pick -x 5fe6e308abaea082c20fbf2aa5df8e14495622cf
# <resolve conflicts, build, test, etc.>
git commit -s
git send-email --to '<[email protected]>' --in-reply-to '2024100247-spray-enjoyable-b1d0@gregkh' --subject-prefix 'PATCH 6.11.y' HEAD^..

Possible dependencies:

5fe6e308abae ("bpf: Fix use-after-free in bpf_uprobe_multi_link_attach()") 3c83a9ad0295 ("uprobes: make uprobe_register() return struct uprobe *") e04332ebc8ac ("uprobes: kill uprobe_register_refctr()") db61e6a4eee5 ("selftests/bpf: fix uprobe.path leak in bpf_testmod")

thanks,

greg k-h

------------------ original commit in Linus's tree ------------------

From 5fe6e308abaea082c20fbf2aa5df8e14495622cf Mon Sep 17 00:00:00 2001
From: Oleg Nesterov <[email protected]>
Date: Tue, 13 Aug 2024 17:25:24 +0200
Subject: [PATCH] bpf: Fix use-after-free in bpf_uprobe_multi_link_attach()

If bpf_link_prime() fails, bpf_uprobe_multi_link_attach() goes to the error_free label and frees the array of bpf_uprobe's without calling bpf_uprobe_unregister().

This leaks bpf_uprobe->uprobe and worse, this frees bpf_uprobe->consumer without removing it from the uprobe->consumers list.

index 4e391daafa64..90cd30e9723e 100644
@@ -3484,17 +3484,20 @@ int bpf_uprobe_multi_link_attach(const union bpf_attr *attr, struct bpf_prog *pr
 						    &uprobes[i].consumer);
 		if (IS_ERR(uprobes[i].uprobe)) {
 			err = PTR_ERR(uprobes[i].uprobe);
-			bpf_uprobe_unregister(uprobes, i);
-			goto error_free;
+			link->cnt = i;
+			goto error_unregister;
 		}
 	}
 
 	err = bpf_link_prime(&link->link, &link_primer);
 	if (err)
-		goto error_free;
+		goto error_unregister;
 
 	return bpf_link_settle(&link_primer);
 
+error_unregister:
+	bpf_uprobe_unregister(uprobes, link->cnt);
+
 error_free:
 	kvfree(uprobes);
 	kfree(link);

Hi Greg,

Please see the attached patch. Should work for 6.11 and the previous versions.

Oleg.

From 69238e2134d57bd7d55c02e1e19fcea75121f21c Mon Sep 17 00:00:00 2001
From: Oleg Nesterov <[email protected]>
Date: Thu, 19 Sep 2024 15:28:53 +0200
Subject: [PATCH -stable] bpf: Fix use-after-free in bpf_uprobe_multi_link_attach()

commit 5fe6e308abaea082c20fbf2aa5df8e14495622cf upstream.

If bpf_link_prime() fails, bpf_uprobe_multi_link_attach() goes to the error_free label and frees the array of bpf_uprobe's without calling bpf_uprobe_unregister().

This leaks bpf_uprobe->uprobe and worse, this frees bpf_uprobe->consumer without removing it from the uprobe->consumers list.

---
 kernel/trace/bpf_trace.c | 9 ++++++---
 1 file changed, 6 insertions(+), 3 deletions(-)

index cd098846e251..af7669a70f2b 100644
@@ -3485,17 +3485,20 @@ int bpf_uprobe_multi_link_attach(const union bpf_attr *attr, struct bpf_prog *pr
 					     uprobes[i].ref_ctr_offset,
 					     &uprobes[i].consumer);
 		if (err) {
-			bpf_uprobe_unregister(&path, uprobes, i);
-			goto error_free;
+			link->cnt = i;
+			goto error_unregister;
 		}
 	}
 
 	err = bpf_link_prime(&link->link, &link_primer);
 	if (err)
-		goto error_free;
+		goto error_unregister;
 
 	return bpf_link_settle(&link_primer);
 
+error_unregister:
+	bpf_uprobe_unregister(&path, uprobes, link->cnt);
+
 error_free:
 	kvfree(uprobes);
 	kfree(link);

2.25.1.362.g51ebf55

Now queued up, thanks.

greg k-h