diff options
| author | Kyle Huey <me@kylehuey.com> | 2024-08-13 15:17:27 +0000 |
|---|---|---|
| committer | Alexei Starovoitov <ast@kernel.org> | 2024-08-13 10:25:28 -0700 |
| commit | 100bff23818eb61751ed05d64a7df36ce9728a4d (patch) | |
| tree | 0fd72c4af5e3f07407caffd2003617df180cdcbe /kernel | |
| parent | 662c3e2db00f92e50c26e9dc4fe47c52223d9982 (diff) | |
perf/bpf: Don't call bpf_overflow_handler() for tracing events
The regressing commit is new in 6.10. It assumed that anytime event->prog
is set bpf_overflow_handler() should be invoked to execute the attached bpf
program. This assumption is false for tracing events, and as a result the
regressing commit broke bpftrace by invoking the bpf handler with garbage
inputs on overflow.
Prior to the regression the overflow handlers formed a chain (of length 0,
1, or 2) and perf_event_set_bpf_handler() (the !tracing case) added
bpf_overflow_handler() to that chain, while perf_event_attach_bpf_prog()
(the tracing case) did not. Both set event->prog. The chain of overflow
handlers was replaced by a single overflow handler slot and a fixed call to
bpf_overflow_handler() when appropriate. This modifies the condition there
to check event->prog->type == BPF_PROG_TYPE_PERF_EVENT, restoring the
previous behavior and fixing bpftrace.
Signed-off-by: Kyle Huey <khuey@kylehuey.com>
Suggested-by: Andrii Nakryiko <andrii.nakryiko@gmail.com>
Reported-by: Joe Damato <jdamato@fastly.com>
Closes: https://lore.kernel.org/lkml/ZpFfocvyF3KHaSzF@LQ3V64L9R2/
Fixes: f11f10bfa1ca ("perf/bpf: Call BPF handler directly, not through overflow machinery")
Cc: stable@vger.kernel.org
Tested-by: Joe Damato <jdamato@fastly.com> # bpftrace
Acked-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/r/20240813151727.28797-1-jdamato@fastly.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Diffstat (limited to 'kernel')
| -rw-r--r-- | kernel/events/core.c | 3 |
1 files changed, 2 insertions, 1 deletions
diff --git a/kernel/events/core.c b/kernel/events/core.c index aa3450bdc227..c973e3c11e03 100644 --- a/kernel/events/core.c +++ b/kernel/events/core.c @@ -9706,7 +9706,8 @@ static int __perf_event_overflow(struct perf_event *event, ret = __perf_event_account_interrupt(event, throttle); - if (event->prog && !bpf_overflow_handler(event, data, regs)) + if (event->prog && event->prog->type == BPF_PROG_TYPE_PERF_EVENT && + !bpf_overflow_handler(event, data, regs)) return ret; /* |