diff options
Diffstat (limited to '0003-cgroup-fix-css_task_iter-crash-on-CSS_TASK_ITER_PROC.patch')
| -rw-r--r-- | 0003-cgroup-fix-css_task_iter-crash-on-CSS_TASK_ITER_PROC.patch | 114 |
1 files changed, 0 insertions, 114 deletions
diff --git a/0003-cgroup-fix-css_task_iter-crash-on-CSS_TASK_ITER_PROC.patch b/0003-cgroup-fix-css_task_iter-crash-on-CSS_TASK_ITER_PROC.patch deleted file mode 100644 index 80a09f9a5469..000000000000 --- a/0003-cgroup-fix-css_task_iter-crash-on-CSS_TASK_ITER_PROC.patch +++ /dev/null @@ -1,114 +0,0 @@ -From a3c64fe9d978f3ee8f21fac5b410c63fe7cce725 Mon Sep 17 00:00:00 2001 -Message-Id: <a3c64fe9d978f3ee8f21fac5b410c63fe7cce725.1514245012.git.jan.steffens@gmail.com> -In-Reply-To: <b0bfa7c33cead5dd87267cfd4c29fda47dc1adc4.1514245012.git.jan.steffens@gmail.com> -References: <b0bfa7c33cead5dd87267cfd4c29fda47dc1adc4.1514245012.git.jan.steffens@gmail.com> -From: Tejun Heo <tj@kernel.org> -Date: Wed, 20 Dec 2017 07:09:19 -0800 -Subject: [PATCH 3/3] cgroup: fix css_task_iter crash on CSS_TASK_ITER_PROC - -While teaching css_task_iter to handle skipping over tasks which -aren't group leaders, bc2fb7ed089f ("cgroup: add @flags to -css_task_iter_start() and implement CSS_TASK_ITER_PROCS") introduced a -silly bug. - -CSS_TASK_ITER_PROCS is implemented by repeating -css_task_iter_advance() while the advanced cursor is pointing to a -non-leader thread. However, the cursor variable, @l, wasn't updated -when the iteration has to advance to the next css_set and the -following repetition would operate on the terminal @l from the -previous iteration which isn't pointing to a valid task leading to -oopses like the following or infinite looping. - - BUG: unable to handle kernel NULL pointer dereference at 0000000000000254 - IP: __task_pid_nr_ns+0xc7/0xf0 - PGD 0 P4D 0 - Oops: 0000 [#1] SMP - ... - CPU: 2 PID: 1 Comm: systemd Not tainted 4.14.4-200.fc26.x86_64 #1 - Hardware name: System manufacturer System Product Name/PRIME B350M-A, BIOS 3203 11/09/2017 - task: ffff88c4baee8000 task.stack: ffff96d5c3158000 - RIP: 0010:__task_pid_nr_ns+0xc7/0xf0 - RSP: 0018:ffff96d5c315bd50 EFLAGS: 00010206 - RAX: 0000000000000000 RBX: ffff88c4b68c6000 RCX: 0000000000000250 - RDX: ffffffffa5e47960 RSI: 0000000000000000 RDI: ffff88c490f6ab00 - RBP: ffff96d5c315bd50 R08: 0000000000001000 R09: 0000000000000005 - R10: ffff88c4be006b80 R11: ffff88c42f1b8004 R12: ffff96d5c315bf18 - R13: ffff88c42d7dd200 R14: ffff88c490f6a510 R15: ffff88c4b68c6000 - FS: 00007f9446f8ea00(0000) GS:ffff88c4be680000(0000) knlGS:0000000000000000 - CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 - CR2: 0000000000000254 CR3: 00000007f956f000 CR4: 00000000003406e0 - Call Trace: - cgroup_procs_show+0x19/0x30 - cgroup_seqfile_show+0x4c/0xb0 - kernfs_seq_show+0x21/0x30 - seq_read+0x2ec/0x3f0 - kernfs_fop_read+0x134/0x180 - __vfs_read+0x37/0x160 - ? security_file_permission+0x9b/0xc0 - vfs_read+0x8e/0x130 - SyS_read+0x55/0xc0 - entry_SYSCALL_64_fastpath+0x1a/0xa5 - RIP: 0033:0x7f94455f942d - RSP: 002b:00007ffe81ba2d00 EFLAGS: 00000293 ORIG_RAX: 0000000000000000 - RAX: ffffffffffffffda RBX: 00005574e2233f00 RCX: 00007f94455f942d - RDX: 0000000000001000 RSI: 00005574e2321a90 RDI: 000000000000002b - RBP: 0000000000000000 R08: 00005574e2321a90 R09: 00005574e231de60 - R10: 00007f94458c8b38 R11: 0000000000000293 R12: 00007f94458c8ae0 - R13: 00007ffe81ba3800 R14: 0000000000000000 R15: 00005574e2116560 - Code: 04 74 0e 89 f6 48 8d 04 76 48 8d 04 c5 f0 05 00 00 48 8b bf b8 05 00 00 48 01 c7 31 c0 48 8b 0f 48 85 c9 74 18 8b b2 30 08 00 00 <3b> 71 04 77 0d 48 c1 e6 05 48 01 f1 48 3b 51 38 74 09 5d c3 8b - RIP: __task_pid_nr_ns+0xc7/0xf0 RSP: ffff96d5c315bd50 - -Fix it by moving the initialization of the cursor below the repeat -label. While at it, rename it to @next for readability. - -Signed-off-by: Tejun Heo <tj@kernel.org> -Fixes: bc2fb7ed089f ("cgroup: add @flags to css_task_iter_start() and implement CSS_TASK_ITER_PROCS") -Cc: stable@vger.kernel.org # v4.14+ -Reported-by: Laura Abbott <labbott@redhat.com> -Reported-by: Bronek Kozicki <brok@incorrekt.com> -Reported-by: George Amanakis <gamanakis@gmail.com> -Signed-off-by: Tejun Heo <tj@kernel.org> ---- - kernel/cgroup/cgroup.c | 14 ++++++-------- - 1 file changed, 6 insertions(+), 8 deletions(-) - -diff --git a/kernel/cgroup/cgroup.c b/kernel/cgroup/cgroup.c -index 44857278eb8aa6a2..030e4286f14c715e 100644 ---- a/kernel/cgroup/cgroup.c -+++ b/kernel/cgroup/cgroup.c -@@ -4059,26 +4059,24 @@ static void css_task_iter_advance_css_set(struct css_task_iter *it) - - static void css_task_iter_advance(struct css_task_iter *it) - { -- struct list_head *l = it->task_pos; -+ struct list_head *next; - - lockdep_assert_held(&css_set_lock); -- WARN_ON_ONCE(!l); -- - repeat: - /* - * Advance iterator to find next entry. cset->tasks is consumed - * first and then ->mg_tasks. After ->mg_tasks, we move onto the - * next cset. - */ -- l = l->next; -+ next = it->task_pos->next; - -- if (l == it->tasks_head) -- l = it->mg_tasks_head->next; -+ if (next == it->tasks_head) -+ next = it->mg_tasks_head->next; - -- if (l == it->mg_tasks_head) -+ if (next == it->mg_tasks_head) - css_task_iter_advance_css_set(it); - else -- it->task_pos = l; -+ it->task_pos = next; - - /* if PROCS, skip over tasks which aren't group leaders */ - if ((it->flags & CSS_TASK_ITER_PROCS) && it->task_pos && --- -2.15.1 - |