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| author | Chris Wilson <chris@chris-wilson.co.uk> | 2019-09-03 09:21:33 +0300 |
|---|---|---|
| committer | Chris Wilson <chris@chris-wilson.co.uk> | 2019-09-06 15:48:46 +0300 |
| commit | a8c15954d64ac7177559c9f5eeb6593e5883fd69 (patch) | |
| tree | 9238749285c9e998482c744b1c51711e0e466356 | |
| parent | aaef851083ed577a4a6094dec3caf7f00f1fd0db (diff) | |
| download | linux-a8c15954d64ac7177559c9f5eeb6593e5883fd69.tar.xz | |
drm/i915: Protect debugfs per_file_stats with RCU lock
If we make sure we grab a strong reference to each object as we dump it,
we can reduce the locks outside of our iterators to an rcu_read_lock.
This should prevent errors like:
[ 2138.371911] BUG: KASAN: use-after-free in per_file_stats+0x43/0x380 [i915]
[ 2138.371924] Read of size 8 at addr ffff888223651000 by task cat/8293
[ 2138.371947] CPU: 0 PID: 8293 Comm: cat Not tainted 5.3.0-rc6-CI-Custom_4352+ #1
[ 2138.371953] Hardware name: To Be Filled By O.E.M. To Be Filled By O.E.M./J4205-ITX, BIOS P1.40 07/14/2017
[ 2138.371959] Call Trace:
[ 2138.371974] dump_stack+0x7c/0xbb
[ 2138.372099] ? per_file_stats+0x43/0x380 [i915]
[ 2138.372108] print_address_description+0x73/0x3a0
[ 2138.372231] ? per_file_stats+0x43/0x380 [i915]
[ 2138.372352] ? per_file_stats+0x43/0x380 [i915]
[ 2138.372362] __kasan_report+0x14e/0x192
[ 2138.372489] ? per_file_stats+0x43/0x380 [i915]
[ 2138.372502] kasan_report+0xe/0x20
[ 2138.372625] per_file_stats+0x43/0x380 [i915]
[ 2138.372751] ? i915_panel_show+0x110/0x110 [i915]
[ 2138.372761] idr_for_each+0xa7/0x160
[ 2138.372773] ? idr_get_next_ul+0x110/0x110
[ 2138.372782] ? do_raw_spin_lock+0x10a/0x1d0
[ 2138.372923] print_context_stats+0x264/0x510 [i915]
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Tested-by: David Weinehall <david.weinehall@linux.intel.com>
Reviewed-by: Mika Kuoppala <mika.kuoppala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20190903062133.27360-1-chris@chris-wilson.co.uk
| -rw-r--r-- | drivers/gpu/drm/i915/i915_debugfs.c | 10 |
1 files changed, 8 insertions, 2 deletions
diff --git a/drivers/gpu/drm/i915/i915_debugfs.c b/drivers/gpu/drm/i915/i915_debugfs.c index 9798f27a697a..708855e051b5 100644 --- a/drivers/gpu/drm/i915/i915_debugfs.c +++ b/drivers/gpu/drm/i915/i915_debugfs.c @@ -237,6 +237,9 @@ static int per_file_stats(int id, void *ptr, void *data) struct file_stats *stats = data; struct i915_vma *vma; + if (!kref_get_unless_zero(&obj->base.refcount)) + return 0; + stats->count++; stats->total += obj->base.size; if (!atomic_read(&obj->bind_count)) @@ -284,6 +287,7 @@ static int per_file_stats(int id, void *ptr, void *data) } spin_unlock(&obj->vma.lock); + i915_gem_object_put(obj); return 0; } @@ -313,10 +317,12 @@ static void print_context_stats(struct seq_file *m, i915_gem_context_lock_engines(ctx), it) { intel_context_lock_pinned(ce); if (intel_context_is_pinned(ce)) { + rcu_read_lock(); if (ce->state) per_file_stats(0, ce->state->obj, &kstats); per_file_stats(0, ce->ring->vma->obj, &kstats); + rcu_read_unlock(); } intel_context_unlock_pinned(ce); } @@ -328,9 +334,9 @@ static void print_context_stats(struct seq_file *m, struct task_struct *task; char name[80]; - spin_lock(&file->table_lock); + rcu_read_lock(); idr_for_each(&file->object_idr, per_file_stats, &stats); - spin_unlock(&file->table_lock); + rcu_read_unlock(); rcu_read_lock(); task = pid_task(ctx->pid ?: file->pid, PIDTYPE_PID); |