--- /dev/null
+From f91072ed1b7283b13ca57fcfbece5a3b92726143 Mon Sep 17 00:00:00 2001
+From: Jiri Olsa <jolsa@redhat.com>
+Date: Wed, 16 Sep 2020 13:53:11 +0200
+Subject: perf/core: Fix race in the perf_mmap_close() function
+
+From: Jiri Olsa <jolsa@redhat.com>
+
+commit f91072ed1b7283b13ca57fcfbece5a3b92726143 upstream.
+
+There's a possible race in perf_mmap_close() when checking ring buffer's
+mmap_count refcount value. The problem is that the mmap_count check is
+not atomic because we call atomic_dec() and atomic_read() separately.
+
+ perf_mmap_close:
+ ...
+ atomic_dec(&rb->mmap_count);
+ ...
+ if (atomic_read(&rb->mmap_count))
+ goto out_put;
+
+ <ring buffer detach>
+ free_uid
+
+out_put:
+ ring_buffer_put(rb); /* could be last */
+
+The race can happen when we have two (or more) events sharing same ring
+buffer and they go through atomic_dec() and then they both see 0 as refcount
+value later in atomic_read(). Then both will go on and execute code which
+is meant to be run just once.
+
+The code that detaches ring buffer is probably fine to be executed more
+than once, but the problem is in calling free_uid(), which will later on
+demonstrate in related crashes and refcount warnings, like:
+
+ refcount_t: addition on 0; use-after-free.
+ ...
+ RIP: 0010:refcount_warn_saturate+0x6d/0xf
+ ...
+ Call Trace:
+ prepare_creds+0x190/0x1e0
+ copy_creds+0x35/0x172
+ copy_process+0x471/0x1a80
+ _do_fork+0x83/0x3a0
+ __do_sys_wait4+0x83/0x90
+ __do_sys_clone+0x85/0xa0
+ do_syscall_64+0x5b/0x1e0
+ entry_SYSCALL_64_after_hwframe+0x44/0xa9
+
+Using atomic decrease and check instead of separated calls.
+
+Tested-by: Michael Petlan <mpetlan@redhat.com>
+Signed-off-by: Jiri Olsa <jolsa@kernel.org>
+Signed-off-by: Ingo Molnar <mingo@kernel.org>
+Acked-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
+Acked-by: Namhyung Kim <namhyung@kernel.org>
+Acked-by: Wade Mealing <wmealing@redhat.com>
+Fixes: 9bb5d40cd93c ("perf: Fix mmap() accounting hole");
+Link: https://lore.kernel.org/r/20200916115311.GE2301783@krava
+[sudip: used ring_buffer]
+Signed-off-by: Sudip Mukherjee <sudipm.mukherjee@gmail.com>
+Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
+---
+ kernel/events/core.c | 7 ++++---
+ 1 file changed, 4 insertions(+), 3 deletions(-)
+
+--- a/kernel/events/core.c
++++ b/kernel/events/core.c
+@@ -5207,11 +5207,11 @@ static void perf_pmu_output_stop(struct
+ static void perf_mmap_close(struct vm_area_struct *vma)
+ {
+ struct perf_event *event = vma->vm_file->private_data;
+-
+ struct ring_buffer *rb = ring_buffer_get(event);
+ struct user_struct *mmap_user = rb->mmap_user;
+ int mmap_locked = rb->mmap_locked;
+ unsigned long size = perf_data_size(rb);
++ bool detach_rest = false;
+
+ if (event->pmu->event_unmapped)
+ event->pmu->event_unmapped(event, vma->vm_mm);
+@@ -5242,7 +5242,8 @@ static void perf_mmap_close(struct vm_ar
+ mutex_unlock(&event->mmap_mutex);
+ }
+
+- atomic_dec(&rb->mmap_count);
++ if (atomic_dec_and_test(&rb->mmap_count))
++ detach_rest = true;
+
+ if (!atomic_dec_and_mutex_lock(&event->mmap_count, &event->mmap_mutex))
+ goto out_put;
+@@ -5251,7 +5252,7 @@ static void perf_mmap_close(struct vm_ar
+ mutex_unlock(&event->mmap_mutex);
+
+ /* If there's still other mmap()s of this buffer, we're done. */
+- if (atomic_read(&rb->mmap_count))
++ if (!detach_rest)
+ goto out_put;
+
+ /*
--- /dev/null
+From df5b0ab3e08a156701b537809914b339b0daa526 Mon Sep 17 00:00:00 2001
+From: Matteo Croce <mcroce@microsoft.com>
+Date: Fri, 13 Nov 2020 22:52:07 -0800
+Subject: reboot: fix overflow parsing reboot cpu number
+
+From: Matteo Croce <mcroce@microsoft.com>
+
+commit df5b0ab3e08a156701b537809914b339b0daa526 upstream.
+
+Limit the CPU number to num_possible_cpus(), because setting it to a
+value lower than INT_MAX but higher than NR_CPUS produces the following
+error on reboot and shutdown:
+
+ BUG: unable to handle page fault for address: ffffffff90ab1bb0
+ #PF: supervisor read access in kernel mode
+ #PF: error_code(0x0000) - not-present page
+ PGD 1c09067 P4D 1c09067 PUD 1c0a063 PMD 0
+ Oops: 0000 [#1] SMP
+ CPU: 1 PID: 1 Comm: systemd-shutdow Not tainted 5.9.0-rc8-kvm #110
+ Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.13.0-2.fc32 04/01/2014
+ RIP: 0010:migrate_to_reboot_cpu+0xe/0x60
+ Code: ea ea 00 48 89 fa 48 c7 c7 30 57 f1 81 e9 fa ef ff ff 66 2e 0f 1f 84 00 00 00 00 00 53 8b 1d d5 ea ea 00 e8 14 33 fe ff 89 da <48> 0f a3 15 ea fc bd 00 48 89 d0 73 29 89 c2 c1 e8 06 65 48 8b 3c
+ RSP: 0018:ffffc90000013e08 EFLAGS: 00010246
+ RAX: ffff88801f0a0000 RBX: 0000000077359400 RCX: 0000000000000000
+ RDX: 0000000077359400 RSI: 0000000000000002 RDI: ffffffff81c199e0
+ RBP: ffffffff81c1e3c0 R08: ffff88801f41f000 R09: ffffffff81c1e348
+ R10: 0000000000000000 R11: 0000000000000000 R12: 0000000000000000
+ R13: 00007f32bedf8830 R14: 00000000fee1dead R15: 0000000000000000
+ FS: 00007f32bedf8980(0000) GS:ffff88801f480000(0000) knlGS:0000000000000000
+ CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
+ CR2: ffffffff90ab1bb0 CR3: 000000001d057000 CR4: 00000000000006a0
+ DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
+ DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
+ Call Trace:
+ __do_sys_reboot.cold+0x34/0x5b
+ do_syscall_64+0x2d/0x40
+
+Fixes: 1b3a5d02ee07 ("reboot: move arch/x86 reboot= handling to generic kernel")
+Signed-off-by: Matteo Croce <mcroce@microsoft.com>
+Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
+Cc: Arnd Bergmann <arnd@arndb.de>
+Cc: Fabian Frederick <fabf@skynet.be>
+Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
+Cc: Guenter Roeck <linux@roeck-us.net>
+Cc: Kees Cook <keescook@chromium.org>
+Cc: Mike Rapoport <rppt@kernel.org>
+Cc: Pavel Tatashin <pasha.tatashin@soleen.com>
+Cc: Petr Mladek <pmladek@suse.com>
+Cc: Robin Holt <robinmholt@gmail.com>
+Cc: <stable@vger.kernel.org>
+Link: https://lkml.kernel.org/r/20201103214025.116799-3-mcroce@linux.microsoft.com
+Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
+[sudip: use reboot_mode instead of mode]
+Signed-off-by: Sudip Mukherjee <sudipm.mukherjee@gmail.com>
+Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
+---
+ kernel/reboot.c | 7 +++++++
+ 1 file changed, 7 insertions(+)
+
+--- a/kernel/reboot.c
++++ b/kernel/reboot.c
+@@ -519,6 +519,13 @@ static int __init reboot_setup(char *str
+ reboot_cpu = simple_strtoul(str+3, NULL, 0);
+ else
+ reboot_mode = REBOOT_SOFT;
++ if (reboot_cpu >= num_possible_cpus()) {
++ pr_err("Ignoring the CPU number in reboot= option. "
++ "CPU %d exceeds possible cpu number %d\n",
++ reboot_cpu, num_possible_cpus());
++ reboot_cpu = 0;
++ break;
++ }
+ break;
+
+ case 'g':
--- /dev/null
+From 8b92c4ff4423aa9900cf838d3294fcade4dbda35 Mon Sep 17 00:00:00 2001
+From: Matteo Croce <mcroce@microsoft.com>
+Date: Fri, 13 Nov 2020 22:52:02 -0800
+Subject: Revert "kernel/reboot.c: convert simple_strtoul to kstrtoint"
+
+From: Matteo Croce <mcroce@microsoft.com>
+
+commit 8b92c4ff4423aa9900cf838d3294fcade4dbda35 upstream.
+
+Patch series "fix parsing of reboot= cmdline", v3.
+
+The parsing of the reboot= cmdline has two major errors:
+
+ - a missing bound check can crash the system on reboot
+
+ - parsing of the cpu number only works if specified last
+
+Fix both.
+
+This patch (of 2):
+
+This reverts commit 616feab753972b97.
+
+kstrtoint() and simple_strtoul() have a subtle difference which makes
+them non interchangeable: if a non digit character is found amid the
+parsing, the former will return an error, while the latter will just
+stop parsing, e.g. simple_strtoul("123xyx") = 123.
+
+The kernel cmdline reboot= argument allows to specify the CPU used for
+rebooting, with the syntax `s####` among the other flags, e.g.
+"reboot=warm,s31,force", so if this flag is not the last given, it's
+silently ignored as well as the subsequent ones.
+
+Fixes: 616feab75397 ("kernel/reboot.c: convert simple_strtoul to kstrtoint")
+Signed-off-by: Matteo Croce <mcroce@microsoft.com>
+Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
+Cc: Guenter Roeck <linux@roeck-us.net>
+Cc: Petr Mladek <pmladek@suse.com>
+Cc: Arnd Bergmann <arnd@arndb.de>
+Cc: Mike Rapoport <rppt@kernel.org>
+Cc: Kees Cook <keescook@chromium.org>
+Cc: Pavel Tatashin <pasha.tatashin@soleen.com>
+Cc: Robin Holt <robinmholt@gmail.com>
+Cc: Fabian Frederick <fabf@skynet.be>
+Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
+Cc: <stable@vger.kernel.org>
+Link: https://lkml.kernel.org/r/20201103214025.116799-2-mcroce@linux.microsoft.com
+Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
+[sudip: use reboot_mode instead of mode]
+Signed-off-by: Sudip Mukherjee <sudipm.mukherjee@gmail.com>
+Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
+---
+ kernel/reboot.c | 21 +++++++--------------
+ 1 file changed, 7 insertions(+), 14 deletions(-)
+
+--- a/kernel/reboot.c
++++ b/kernel/reboot.c
+@@ -512,22 +512,15 @@ static int __init reboot_setup(char *str
+ break;
+
+ case 's':
+- {
+- int rc;
+-
+- if (isdigit(*(str+1))) {
+- rc = kstrtoint(str+1, 0, &reboot_cpu);
+- if (rc)
+- return rc;
+- } else if (str[1] == 'm' && str[2] == 'p' &&
+- isdigit(*(str+3))) {
+- rc = kstrtoint(str+3, 0, &reboot_cpu);
+- if (rc)
+- return rc;
+- } else
++ if (isdigit(*(str+1)))
++ reboot_cpu = simple_strtoul(str+1, NULL, 0);
++ else if (str[1] == 'm' && str[2] == 'p' &&
++ isdigit(*(str+3)))
++ reboot_cpu = simple_strtoul(str+3, NULL, 0);
++ else
+ reboot_mode = REBOOT_SOFT;
+ break;
+- }
++
+ case 'g':
+ reboot_mode = REBOOT_GPIO;
+ break;
xen-events-use-a-common-cpu-hotplug-hook-for-event-channels.patch
xen-events-defer-eoi-in-case-of-excessive-number-of-events.patch
xen-events-block-rogue-events-for-some-time.patch
+perf-core-fix-race-in-the-perf_mmap_close-function.patch
+revert-kernel-reboot.c-convert-simple_strtoul-to-kstrtoint.patch
+reboot-fix-overflow-parsing-reboot-cpu-number.patch
projects / thirdparty / kernel / stable-queue.git / commitdiff
