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Fri, 24 May 2024 17:17:42 +0800 Received: from mtksdccf07.mediatek.inc (172.21.84.99) by mtkmbs13n2.mediatek.inc (172.21.101.73) with Microsoft SMTP Server id 15.2.1118.26 via Frontend Transport; Fri, 24 May 2024 17:17:41 +0800 From: dicken.ding To: Thomas Gleixner , Matthias Brugger , AngeloGioacchino Del Regno CC: , , , , , , , dicken.ding Subject: [PATCH v2] genirq: Fix uaf issue in irq_find_at_or_after Date: Fri, 24 May 2024 17:17:39 +0800 Message-ID: <20240524091739.31611-1-dicken.ding@mediatek.com> X-Mailer: git-send-email 2.18.0 MIME-Version: 1.0 X-TM-AS-Product-Ver: SMEX-14.0.0.3152-9.1.1006-23728.005 X-TM-AS-Result: No-10-0.765600-8.000000 X-TMASE-MatchedRID: E9R+qDaxr1ctJMbDWD8p3s36paW7ZnFoShVPkKm2lvom8HVb/vaoaBjb R/XCsHXWZcp+cbcMclYprKt88L0dYRHdGMlurS25GVyS87Wb4lwEa8g1x8eqF004B0iWfKShoPP mGyJpwt+csAFBY7MGhmMyV758esm2dbriIxqwTjzYhNMNlv+0N23eqxoVjgMEAqhgvqvZVjrj6f SiVX5AvyFeLvGCnXirAbY5HH0TJqmR9GF2J2xqMxRFJJyf5BJerSFs54Y4wbX6C0ePs7A07fVTw 0XgOy3aD7wXD1GnDwt3Bi3EmJ+ppptr4Hl7Wsk/0u3TjrxHFhhzcmzHPtSQ/6qSeetSSaOf61U+ rWxzl6orZuODv9rCwDfSLz0+kBezdmtRsRmKkASJZPT2ZDPuzPD2QfzMDLjhIh26TkmSN3dVyvb Tg/runA== X-TM-AS-User-Approved-Sender: No X-TM-AS-User-Blocked-Sender: No X-TMASE-Result: 10-0.765600-8.000000 X-TMASE-Version: SMEX-14.0.0.3152-9.1.1006-23728.005 X-TM-SNTS-SMTP: 5C4EE66FCDD525C442DA716EA1562D25AED399B840A0DCAEB36B7E777895CD6D2000:8 X-MTK: N X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20240524_021823_126598_035EB38F X-CRM114-Status: GOOD ( 13.74 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org irq_find_at_or_after() is at the risk of use-after-free due to lack of any locks. 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 deference. Here is an example:: CPU0 CPU1 mt_find() delayed_free_desc() irq_desc_get_irq() The use-after-free issue is reported by KASAN, as shown in the following log:: Call trace: dump_backtrace+0xec/0x138 show_stack+0x18/0x24 dump_stack_lvl+0x50/0x6c print_report+0x1b0/0x714 kasan_report+0xc4/0x124 __do_kernel_fault+0xc0/0x368 do_bad_area+0x30/0xdc do_tag_check_fault+0x20/0x34 do_mem_abort+0x58/0x118 el1_abort+0x3c/0x5c el1h_64_sync_handler+0x54/0x90 el1h_64_sync+0x68/0x6c 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 __arm64_sys_pread64+0x84/0xcc invoke_syscall+0x58/0x114 el0_svc_common+0x80/0xe0 do_el0_svc+0x1c/0x28 el0_svc+0x38/0x68 el0t_64_sync_handler+0x68/0xbc el0t_64_sync+0x1a8/0x1ac Freed by task 4471: kasan_save_stack+0x40/0x70 save_stack_info+0x34/0x128 kasan_save_free_info+0x18/0x28 ____kasan_slab_free+0x254/0x25c __kasan_slab_free+0x10/0x20 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 rcu_core+0x1b0/0x408 rcu_core_si+0x10/0x20 __do_softirq+0x154/0x470 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 --- Changes since v1: - Use guard(rcu)() to guard the access based on Thomas Gleixner's suggestion. - Modify the commit message. --- 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 88ac3652fcf2..07e99c936ba5 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; }