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lib: cpu_rmap: Avoid use after free on rmap->obj array entries

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When calling irq_set_affinity_notifier() with NULL at the notify
argument, it will cause freeing of the glue pointer in the
corresponding array entry but will leave the pointer in the array. A
subsequent call to free_irq_cpu_rmap() will try to free this entry again
leading to possible use after free.

Fix that by setting NULL to the array entry and checking that we have
non-zero at the array entry when iterating over the array in
free_irq_cpu_rmap().

The current code does not suffer from this since there are no cases
where irq_set_affinity_notifier(irq, NULL) (note the NULL passed for the
notify arg) is called, followed by a call to free_irq_cpu_rmap() so we
don't hit and issue. Subsequent patches in this series excersize this
flow, hence the required fix.

Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Eli Cohen <elic@nvidia.com>
Signed-off-by: Saeed Mahameed <saeedm@nvidia.com>
Reviewed-by: Jacob Keller <jacob.e.keller@intel.com>
This commit is contained in:
Eli Cohen 2023-02-08 07:51:02 +02:00 committed by Saeed Mahameed
parent e8d018dd02
commit 4e0473f106
1 changed files with 4 additions and 1 deletions
repo.diff.show_diff_stats Download patch file Download diff file Expand all files Collapse all files

5
lib/cpu_rmap.c
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@ -232,7 +232,8 @@ void free_irq_cpu_rmap(struct cpu_rmap *rmap)
for (index = 0; index < rmap->used; index++) { for (index = 0; index < rmap->used; index++) {
glue = rmap->obj[index]; glue = rmap->obj[index];
irq_set_affinity_notifier(glue->notify.irq, NULL); if (glue)
irq_set_affinity_notifier(glue->notify.irq, NULL);
} }
cpu_rmap_put(rmap); cpu_rmap_put(rmap);
@ -268,6 +269,7 @@ static void irq_cpu_rmap_release(struct kref *ref)
container_of(ref, struct irq_glue, notify.kref); container_of(ref, struct irq_glue, notify.kref);
cpu_rmap_put(glue->rmap); cpu_rmap_put(glue->rmap);
glue->rmap->obj[glue->index] = NULL;
kfree(glue); kfree(glue);
} }
@ -297,6 +299,7 @@ int irq_cpu_rmap_add(struct cpu_rmap *rmap, int irq)
rc = irq_set_affinity_notifier(irq, &glue->notify); rc = irq_set_affinity_notifier(irq, &glue->notify);
if (rc) { if (rc) {
cpu_rmap_put(glue->rmap); cpu_rmap_put(glue->rmap);
rmap->obj[glue->index] = NULL;
kfree(glue); kfree(glue);
} }
return rc; return rc;