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linux/include/uapi
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Jordan Rome 49c4d6fe85 bpf: Add crosstask check to __bpf_get_stack 
[ Upstream commit b8e3a87a62 ]

Currently get_perf_callchain only supports user stack walking for
the current task. Passing the correct *crosstask* param will return
0 frames if the task passed to __bpf_get_stack isn't the current
one instead of a single incorrect frame/address. This change
passes the correct *crosstask* param but also does a preemptive
check in __bpf_get_stack if the task is current and returns
-EOPNOTSUPP if it is not.

This issue was found using bpf_get_task_stack inside a BPF
iterator ("iter/task"), which iterates over all tasks.
bpf_get_task_stack works fine for fetching kernel stacks
but because get_perf_callchain relies on the caller to know
if the requested *task* is the current one (via *crosstask*)
it was failing in a confusing way.

It might be possible to get user stacks for all tasks utilizing
something like access_process_vm but that requires the bpf
program calling bpf_get_task_stack to be sleepable and would
therefore be a breaking change.

Fixes: fa28dcb82a ("bpf: Introduce helper bpf_get_task_stack()")
Signed-off-by: Jordan Rome <jordalgo@meta.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20231108112334.3433136-1-jordalgo@meta.com
Signed-off-by: Sasha Levin <sashal@kernel.org>
History 2024-01-25 15:44:45 -08:00
..
asm-generic asm-generic updates for v6.7 2023-11-01 15:28:33 -10:00
drm Merge tag 'drm-misc-next-2023-10-27' of git://anongit.freedesktop.org/drm/drm-misc into drm-next 2023-10-31 10:47:50 +10:00
linux bpf: Add crosstask check to __bpf_get_stack 2024-01-25 15:44:45 -08:00
misc habanalabs/uapi: move uapi file to drm 2023-01-26 10:56:23 +02:00
mtd ubi: fastmap: Add control in 'UBI_IOCATT' ioctl to reserve PEBs for filling pools 2023-10-28 23:16:00 +02:00
rdma RDMA/core: Add support to set privileged QKEY parameter 2023-10-19 09:31:00 +03:00
scsi Merge branch 'fixes' into misc 2023-09-02 08:25:19 +01:00
sound ALSA: seq: Replace with __packed attribute 2023-10-26 09:43:28 +02:00
video License cleanup: add SPDX license identifier to uapi header files with a license 2017-11-02 11:20:11 +01:00
xen xen: privcmd: Add support for ioeventfd 2023-10-16 15:18:33 +02:00
Kbuild kbuild: re-implement Makefile.headersinst without recursion 2019-06-15 19:57:02 +09:00