Commit 8a1045d9 authored by dicken.ding's avatar dicken.ding Committed by Liao Chen
Browse files

genirq/irqdesc: Prevent use-after-free in irq_find_at_or_after() 

mainline inclusion
from mainline-v6.10-rc1
commit b84a8aba806261d2f759ccedf4a2a6a80a5e55ba
category: bugfix
bugzilla: https://gitee.com/openeuler/kernel/issues/IA985V
CVE: CVE-2024-38385

Reference: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=b84a8aba806261d2f759ccedf4a2a6a80a5e55ba



--------------------------------

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: 721255b9 ("genirq: Use a maple tree for interrupt descriptor management")
Signed-off-by: default avatardicken.ding <dicken.ding@mediatek.com>
Signed-off-by: default avatarThomas Gleixner <tglx@linutronix.de>
Cc: stable@vger.kernel.org
Link: https://lore.kernel.org/r/20240524091739.31611-1-dicken.ding@mediatek.com


Signed-off-by: default avatarLiao Chen <liaochen4@huawei.com>
parent 5e48db30

kernel/irq/irqdesc.c

+4 −1
Original line number Diff line number Diff line
@@ -148,7 +148,10 @@ 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;

}