user/sven/linux.git/kernel/panic.c, branch v5.4.251

exit: Use READ_ONCE() for all oops/warn limit reads

2023-02-06T06:52:50Z

commit 7535b832c6399b5ebfc5b53af5c51dd915ee2538 upstream. Use a temporary variable to take full advantage of READ_ONCE() behavior. Without this, the report (and even the test) might be out of sync with the initial test. Reported-by: Peter Zijlstra Link: https://lore.kernel.org/lkml/Y5x7GXeluFmZ8E0E@hirez.programming.kicks-ass.net Fixes: 9fc9e278a5c0 ("panic: Introduce warn_limit") Fixes: d4ccd54d28d3 ("exit: Put an upper limit on how often we can oops") Cc: "Eric W. Biederman" Cc: Jann Horn Cc: Arnd Bergmann Cc: Petr Mladek Cc: Andrew Morton Cc: Luis Chamberlain Cc: Marco Elver Cc: tangmeng Cc: Sebastian Andrzej Siewior Cc: Tiezhu Yang Signed-off-by: Kees Cook Signed-off-by: Eric Biggers Signed-off-by: Sasha Levin

panic: Expose "warn_count" to sysfs

2023-02-06T06:52:50Z

commit 8b05aa26336113c4cea25f1c333ee8cd4fc212a6 upstream. Since Warn count is now tracked and is a fairly interesting signal, add the entry /sys/kernel/warn_count to expose it to userspace. Cc: Petr Mladek Cc: Andrew Morton Cc: tangmeng Cc: "Guilherme G. Piccoli" Cc: Sebastian Andrzej Siewior Cc: Tiezhu Yang Reviewed-by: Luis Chamberlain Signed-off-by: Kees Cook Link: https://lore.kernel.org/r/20221117234328.594699-6-keescook@chromium.org Signed-off-by: Eric Biggers Signed-off-by: Sasha Levin

panic: Introduce warn_limit

2023-02-06T06:52:50Z

commit 9fc9e278a5c0b708eeffaf47d6eb0c82aa74ed78 upstream. Like oops_limit, add warn_limit for limiting the number of warnings when panic_on_warn is not set. Cc: Jonathan Corbet Cc: Andrew Morton Cc: Baolin Wang Cc: "Jason A. Donenfeld" Cc: Eric Biggers Cc: Huang Ying Cc: Petr Mladek Cc: tangmeng Cc: "Guilherme G. Piccoli" Cc: Tiezhu Yang Cc: Sebastian Andrzej Siewior Cc: linux-doc@vger.kernel.org Reviewed-by: Luis Chamberlain Signed-off-by: Kees Cook Link: https://lore.kernel.org/r/20221117234328.594699-5-keescook@chromium.org Signed-off-by: Eric Biggers Signed-off-by: Sasha Levin

panic: Consolidate open-coded panic_on_warn checks

2023-02-06T06:52:50Z

commit 79cc1ba7badf9e7a12af99695a557e9ce27ee967 upstream. Several run-time checkers (KASAN, UBSAN, KFENCE, KCSAN, sched) roll their own warnings, and each check "panic_on_warn". Consolidate this into a single function so that future instrumentation can be added in a single location. Cc: Marco Elver Cc: Dmitry Vyukov Cc: Ingo Molnar Cc: Peter Zijlstra Cc: Juri Lelli Cc: Vincent Guittot Cc: Dietmar Eggemann Cc: Steven Rostedt Cc: Ben Segall Cc: Mel Gorman Cc: Daniel Bristot de Oliveira Cc: Valentin Schneider Cc: Andrey Ryabinin Cc: Alexander Potapenko Cc: Andrey Konovalov Cc: Vincenzo Frascino Cc: Andrew Morton Cc: David Gow Cc: tangmeng Cc: Jann Horn Cc: Shuah Khan Cc: Petr Mladek Cc: "Paul E. McKenney" Cc: Sebastian Andrzej Siewior Cc: "Guilherme G. Piccoli" Cc: Tiezhu Yang Cc: kasan-dev@googlegroups.com Cc: linux-mm@kvack.org Reviewed-by: Luis Chamberlain Signed-off-by: Kees Cook Reviewed-by: Marco Elver Reviewed-by: Andrey Konovalov Link: https://lore.kernel.org/r/20221117234328.594699-4-keescook@chromium.org Signed-off-by: Eric Biggers Signed-off-by: Sasha Levin

panic: unset panic_on_warn inside panic()

2023-02-06T06:52:48Z

commit 1a2383e8b84c0451fd9b1eec3b9aab16f30b597c upstream. In the current code, the following three places need to unset panic_on_warn before calling panic() to avoid recursive panics: kernel/kcsan/report.c: print_report() kernel/sched/core.c: __schedule_bug() mm/kfence/report.c: kfence_report_error() In order to avoid copy-pasting "panic_on_warn = 0" all over the places, it is better to move it inside panic() and then remove it from the other places. Link: https://lkml.kernel.org/r/1644324666-15947-4-git-send-email-yangtiezhu@loongson.cn Signed-off-by: Tiezhu Yang Reviewed-by: Marco Elver Cc: Andrey Ryabinin Cc: Baoquan He Cc: Jonathan Corbet Cc: Xuefeng Li Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds Signed-off-by: Eric Biggers Signed-off-by: Sasha Levin

panic: ensure preemption is disabled during panic()

2019-10-07T22:47:19Z

Calling 'panic()' on a kernel with CONFIG_PREEMPT=y can leave the calling CPU in an infinite loop, but with interrupts and preemption enabled. From this state, userspace can continue to be scheduled, despite the system being "dead" as far as the kernel is concerned. This is easily reproducible on arm64 when booting with "nosmp" on the command line; a couple of shell scripts print out a periodic "Ping" message whilst another triggers a crash by writing to /proc/sysrq-trigger: | sysrq: Trigger a crash | Kernel panic - not syncing: sysrq triggered crash | CPU: 0 PID: 1 Comm: init Not tainted 5.2.15 #1 | Hardware name: linux,dummy-virt (DT) | Call trace: | dump_backtrace+0x0/0x148 | show_stack+0x14/0x20 | dump_stack+0xa0/0xc4 | panic+0x140/0x32c | sysrq_handle_reboot+0x0/0x20 | __handle_sysrq+0x124/0x190 | write_sysrq_trigger+0x64/0x88 | proc_reg_write+0x60/0xa8 | __vfs_write+0x18/0x40 | vfs_write+0xa4/0x1b8 | ksys_write+0x64/0xf0 | __arm64_sys_write+0x14/0x20 | el0_svc_common.constprop.0+0xb0/0x168 | el0_svc_handler+0x28/0x78 | el0_svc+0x8/0xc | Kernel Offset: disabled | CPU features: 0x0002,24002004 | Memory Limit: none | ---[ end Kernel panic - not syncing: sysrq triggered crash ]--- | Ping 2! | Ping 1! | Ping 1! | Ping 2! The issue can also be triggered on x86 kernels if CONFIG_SMP=n, otherwise local interrupts are disabled in 'smp_send_stop()'. Disable preemption in 'panic()' before re-enabling interrupts. Link: http://lkml.kernel.org/r/20191002123538.22609-1-will@kernel.org Link: https://lore.kernel.org/r/BX1W47JXPMR8.58IYW53H6M5N@dragonstone Signed-off-by: Will Deacon Reported-by: Xogium Reviewed-by: Kees Cook Cc: Russell King Cc: Greg Kroah-Hartman Cc: Ingo Molnar Cc: Petr Mladek Cc: Feng Tang Cc: Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

bug: consolidate __WARN_FLAGS usage

2019-09-26T00:51:41Z

Instead of having separate tests for __WARN_FLAGS, merge the two #ifdef blocks and replace the synonym WANT_WARN_ON_SLOWPATH macro. Link: http://lkml.kernel.org/r/20190819234111.9019-7-keescook@chromium.org Signed-off-by: Kees Cook Cc: Arnd Bergmann Cc: Borislav Petkov Cc: Christophe Leroy Cc: Drew Davenport Cc: Feng Tang Cc: Mauro Carvalho Chehab Cc: Peter Zijlstra Cc: Petr Mladek Cc: "Steven Rostedt (VMware)" Cc: YueHaibing Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

bug: lift "cut here" out of __warn()

2019-09-26T00:51:40Z

In preparation for cleaning up "cut here", move the "cut here" logic up out of __warn() and into callers that pass non-NULL args. For anyone looking closely, there are two callers that pass NULL args: one already explicitly prints "cut here". The remaining case is covered by how a WARN is built, which will be cleaned up in the next patch. Link: http://lkml.kernel.org/r/20190819234111.9019-5-keescook@chromium.org Signed-off-by: Kees Cook Cc: Arnd Bergmann Cc: Borislav Petkov Cc: Christophe Leroy Cc: Drew Davenport Cc: Feng Tang Cc: Mauro Carvalho Chehab Cc: Peter Zijlstra Cc: Petr Mladek Cc: "Steven Rostedt (VMware)" Cc: YueHaibing Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

bug: consolidate warn_slowpath_fmt() usage

2019-09-26T00:51:40Z

Instead of having a separate helper for no printk output, just consolidate the logic into warn_slowpath_fmt(). Link: http://lkml.kernel.org/r/20190819234111.9019-4-keescook@chromium.org Signed-off-by: Kees Cook Cc: Arnd Bergmann Cc: Borislav Petkov Cc: Christophe Leroy Cc: Drew Davenport Cc: Feng Tang Cc: Mauro Carvalho Chehab Cc: Peter Zijlstra Cc: Petr Mladek Cc: "Steven Rostedt (VMware)" Cc: YueHaibing Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

bug: refactor away warn_slowpath_fmt_taint()

2019-09-26T00:51:40Z

Patch series "Clean up WARN() "cut here" handling", v2. Christophe Leroy noticed that the fix for missing "cut here" in the WARN() case was adding explicit printk() calls instead of teaching the exception handler to add it. This refactors the bug/warn infrastructure to pass this information as a new BUGFLAG. Longer details repeated from the last patch in the series: bug: move WARN_ON() "cut here" into exception handler The original cleanup of "cut here" missed the WARN_ON() case (that does not have a printk message), which was fixed recently by adding an explicit printk of "cut here". This had the downside of adding a printk() to every WARN_ON() caller, which reduces the utility of using an instruction exception to streamline the resulting code. By making this a new BUGFLAG, all of these can be removed and "cut here" can be handled by the exception handler. This was very pronounced on PowerPC, but the effect can be seen on x86 as well. The resulting text size of a defconfig build shows some small savings from this patch: text data bss dec hex filename 19691167 5134320 1646664 26472151 193eed7 vmlinux.before 19676362 5134260 1663048 26473670 193f4c6 vmlinux.after This change also opens the door for creating something like BUG_MSG(), where a custom printk() before issuing BUG(), without confusing the "cut here" line. This patch (of 7): There's no reason to have specialized helpers for passing the warn taint down to __warn(). Consolidate and refactor helper macros, removing __WARN_printf() and warn_slowpath_fmt_taint(). Link: http://lkml.kernel.org/r/20190819234111.9019-2-keescook@chromium.org Signed-off-by: Kees Cook Cc: Christophe Leroy Cc: Peter Zijlstra Cc: Christophe Leroy Cc: Drew Davenport Cc: Arnd Bergmann Cc: "Steven Rostedt (VMware)" Cc: Feng Tang Cc: Petr Mladek Cc: Mauro Carvalho Chehab Cc: Borislav Petkov Cc: YueHaibing Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds