The following commit has been merged into the irq/urgent branch of tip:
Commit-ID: b84a8aba806261d2f759ccedf4a2a6a80a5e55ba
Gitweb: https://git.kernel.org/tip/b84a8aba806261d2f759ccedf4a2a6a80a5e55ba
Author: dicken.ding <dicken.ding@xxxxxxxxxxxx>
AuthorDate: Fri, 24 May 2024 17:17:39 +08:00
Committer: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
CommitterDate: Fri, 24 May 2024 12:49:35 +02:00
genirq/irqdesc: Prevent use-after-free in irq_find_at_or_after()
irq_find_at_or_after() dereferences the interrupt descriptor which is
returned by mt_find() while neither holding sparse_irq_lock nor RCU read
lock, which means the descriptor can be freed between mt_find() and the
dereference:
CPU0 CPU1
desc = mt_find()
delayed_free_desc(desc)
irq_desc_get_irq(desc)
The use-after-free is reported by KASAN:
Call trace:
irq_get_next_irq+0x58/0x84
show_stat+0x638/0x824
seq_read_iter+0x158/0x4ec
proc_reg_read_iter+0x94/0x12c
vfs_read+0x1e0/0x2c8
Freed by task 4471:
slab_free_freelist_hook+0x174/0x1e0
__kmem_cache_free+0xa4/0x1dc
kfree+0x64/0x128
irq_kobj_release+0x28/0x3c
kobject_put+0xcc/0x1e0
delayed_free_desc+0x14/0x2c
rcu_do_batch+0x214/0x720
Guard the access with a RCU read lock section.
Fixes: 721255b9826b ("genirq: Use a maple tree for interrupt descriptor management")
Signed-off-by: dicken.ding <dicken.ding@xxxxxxxxxxxx>
Signed-off-by: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Cc: stable@xxxxxxxxxxxxxxx
Link: https://lore.kernel.org/r/20240524091739.31611-1-dicken.ding@xxxxxxxxxxxx
---
kernel/irq/irqdesc.c | 5 ++++-
1 file changed, 4 insertions(+), 1 deletion(-)
diff --git a/kernel/irq/irqdesc.c b/kernel/irq/irqdesc.c
index 88ac365..07e99c9 100644
--- a/kernel/irq/irqdesc.c
+++ b/kernel/irq/irqdesc.c
@@ -160,7 +160,10 @@ static int irq_find_free_area(unsigned int from, unsigned int cnt)
static unsigned int irq_find_at_or_after(unsigned int offset)
{
unsigned long index = offset;
- struct irq_desc *desc = mt_find(&sparse_irqs, &index, nr_irqs);
+ struct irq_desc *desc;
+
+ guard(rcu)();
+ desc = mt_find(&sparse_irqs, &index, nr_irqs);
return desc ? irq_desc_get_irq(desc) : nr_irqs;
}
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