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Andrey Konovalov d0137ce03f kcov: properly check for softirq context
commit 7d4df2dad3 upstream.

When collecting coverage from softirqs, KCOV uses in_serving_softirq() to
check whether the code is running in the softirq context.  Unfortunately,
in_serving_softirq() is > 0 even when the code is running in the hardirq
or NMI context for hardirqs and NMIs that happened during a softirq.

As a result, if a softirq handler contains a remote coverage collection
section and a hardirq with another remote coverage collection section
happens during handling the softirq, KCOV incorrectly detects a nested
softirq coverate collection section and prints a WARNING, as reported by
syzbot.

This issue was exposed by commit a7f3813e58 ("usb: gadget: dummy_hcd:
Switch to hrtimer transfer scheduler"), which switched dummy_hcd to using
hrtimer and made the timer's callback be executed in the hardirq context.

Change the related checks in KCOV to account for this behavior of
in_serving_softirq() and make KCOV ignore remote coverage collection
sections in the hardirq and NMI contexts.

This prevents the WARNING printed by syzbot but does not fix the inability
of KCOV to collect coverage from the __usb_hcd_giveback_urb when dummy_hcd
is in use (caused by a7f3813e58); a separate patch is required for that.

Link: https://lkml.kernel.org/r/20240729022158.92059-1-andrey.konovalov@linux.dev
Fixes: 5ff3b30ab5 ("kcov: collect coverage from interrupts")
Signed-off-by: Andrey Konovalov <andreyknvl@gmail.com>
Reported-by: syzbot+2388cdaeb6b10f0c13ac@syzkaller.appspotmail.com
Closes: https://syzkaller.appspot.com/bug?extid=2388cdaeb6b10f0c13ac
Acked-by: Marco Elver <elver@google.com>
Cc: Alan Stern <stern@rowland.harvard.edu>
Cc: Aleksandr Nogikh <nogikh@google.com>
Cc: Alexander Potapenko <glider@google.com>
Cc: Dmitry Vyukov <dvyukov@google.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Marcello Sylvester Bauer <sylv@sylv.io>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2024-08-14 13:58:57 +02:00
arch parisc: fix a possible DMA corruption 2024-08-14 13:58:57 +02:00
block block: fix deadlock between sd_remove & sd_release 2024-08-03 08:54:24 +02:00
certs
crypto crypto: aead,cipher - zeroize key buffer after use 2024-07-11 12:49:04 +02:00
Documentation clocksource: Scale the watchdog read retries automatically 2024-08-14 13:58:56 +02:00
drivers serial: core: check uartclk for zero to avoid divide by zero 2024-08-14 13:58:57 +02:00
fs tracefs: Use generic inode RCU for synchronizing freeing 2024-08-14 13:58:56 +02:00
include tracefs: Use generic inode RCU for synchronizing freeing 2024-08-14 13:58:56 +02:00
init rust: SHADOW_CALL_STACK is incompatible with Rust 2024-08-11 12:47:24 +02:00
io_uring io_uring: fix io_match_task must_hold 2024-08-03 08:54:41 +02:00
ipc sysctl: treewide: drop unused argument ctl_table_root::set_ownership(table) 2024-08-11 12:47:13 +02:00
kernel kcov: properly check for softirq context 2024-08-14 13:58:57 +02:00
lib lib/build_OID_registry: don't mention the full path of the script in output 2024-08-03 08:54:32 +02:00
LICENSES
mm memcg: protect concurrent access to mem_cgroup_idr 2024-08-14 13:58:57 +02:00
net net: drop bad gso csum_start and offset in virtio_net_hdr 2024-08-14 13:58:48 +02:00
rust rust: kernel: require Send for Module implementations 2024-05-17 12:01:56 +02:00
samples work around gcc bugs with 'asm goto' with outputs 2024-02-23 09:24:47 +01:00
scripts kbuild: avoid build error when single DTB is turned into composite DTB 2024-08-03 08:54:36 +02:00
security apparmor: Fix null pointer deref when receiving skb during sock creation 2024-08-03 08:54:38 +02:00
sound ASoC: amd: yc: Add quirk entry for OMEN by HP Gaming Laptop 16-n0xxx 2024-08-14 13:58:57 +02:00
tools clocksource: Scale the watchdog read retries automatically 2024-08-14 13:58:56 +02:00
usr
virt KVM: Fix a data race on last_boosted_vcpu in kvm_vcpu_on_spin() 2024-06-27 13:49:11 +02:00
.clang-format
.cocciconfig
.get_maintainer.ignore
.gitattributes
.gitignore
.mailmap
.rustfmt.toml
COPYING
CREDITS
Kbuild
Kconfig
MAINTAINERS pwm: Rename pwm_apply_state() to pwm_apply_might_sleep() 2024-06-12 11:12:24 +02:00
Makefile Linux 6.6.45 2024-08-11 12:47:28 +02:00
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