On Sun, Dec 15, 2024 at 10:02:07AM +0100, gregkh@xxxxxxxxxxxxxxxxxxx wrote: > > The patch below does not apply to the 5.15-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 <stable@xxxxxxxxxxxxxxx>. hi, there's conflict because 5.15.y is not getting [1] fix (because 5.15.y does not have [2]), I'll send new backport jirka [1] ef1b808e3b7c bpf: Fix UAF via mismatching bpf_prog/attachment RCU flavors [2] 8c7dcb84e3b7 bpf: implement sleepable uprobes by chaining gps > > 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-5.15.y > git checkout FETCH_HEAD > git cherry-pick -x 978c4486cca5c7b9253d3ab98a88c8e769cb9bbd > # <resolve conflicts, build, test, etc.> > git commit -s > git send-email --to '<stable@xxxxxxxxxxxxxxx>' --in-reply-to '2024121506-pancreas-mosaic-0ae0@gregkh' --subject-prefix 'PATCH 5.15.y' HEAD^.. > > Possible dependencies: > > > > thanks, > > greg k-h > > ------------------ original commit in Linus's tree ------------------ > > From 978c4486cca5c7b9253d3ab98a88c8e769cb9bbd Mon Sep 17 00:00:00 2001 > From: Jiri Olsa <jolsa@xxxxxxxxxx> > Date: Sun, 8 Dec 2024 15:25:07 +0100 > Subject: [PATCH] bpf,perf: Fix invalid prog_array access in > perf_event_detach_bpf_prog > > Syzbot reported [1] crash that happens for following tracing scenario: > > - create tracepoint perf event with attr.inherit=1, attach it to the > process and set bpf program to it > - attached process forks -> chid creates inherited event > > the new child event shares the parent's bpf program and tp_event > (hence prog_array) which is global for tracepoint > > - exit both process and its child -> release both events > - first perf_event_detach_bpf_prog call will release tp_event->prog_array > and second perf_event_detach_bpf_prog will crash, because > tp_event->prog_array is NULL > > The fix makes sure the perf_event_detach_bpf_prog checks prog_array > is valid before it tries to remove the bpf program from it. > > [1] https://lore.kernel.org/bpf/Z1MR6dCIKajNS6nU@krava/T/#m91dbf0688221ec7a7fc95e896a7ef9ff93b0b8ad > > Fixes: 0ee288e69d03 ("bpf,perf: Fix perf_event_detach_bpf_prog error handling") > Reported-by: syzbot+2e0d2840414ce817aaac@xxxxxxxxxxxxxxxxxxxxxxxxx > Signed-off-by: Jiri Olsa <jolsa@xxxxxxxxxx> > Signed-off-by: Andrii Nakryiko <andrii@xxxxxxxxxx> > Link: https://lore.kernel.org/bpf/20241208142507.1207698-1-jolsa@xxxxxxxxxx > > diff --git a/kernel/trace/bpf_trace.c b/kernel/trace/bpf_trace.c > index a403b05a7091..1b8db5aee9d3 100644 > --- a/kernel/trace/bpf_trace.c > +++ b/kernel/trace/bpf_trace.c > @@ -2250,6 +2250,9 @@ void perf_event_detach_bpf_prog(struct perf_event *event) > goto unlock; > > old_array = bpf_event_rcu_dereference(event->tp_event->prog_array); > + if (!old_array) > + goto put; > + > ret = bpf_prog_array_copy(old_array, event->prog, NULL, 0, &new_array); > if (ret < 0) { > bpf_prog_array_delete_safe(old_array, event->prog); > @@ -2258,6 +2261,7 @@ void perf_event_detach_bpf_prog(struct perf_event *event) > bpf_prog_array_free_sleepable(old_array); > } > > +put: > /* > * It could be that the bpf_prog is not sleepable (and will be freed > * via normal RCU), but is called from a point that supports sleepable >
