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A out-of-bounds bug can be triggered by an interrupt, the reason for this bug is the lack of checking of register values. In flexcop_pci_isr, the driver reads value from a register and uses it as a dma address. Finally, this address will be passed to the count parameter of find_next_packet. If this value is larger than the size of dma, the index of buffer will be out-of-bounds. Fix this by adding a check after reading the value of the register. The following KASAN report reveals it: BUG: KASAN: slab-out-of-bounds in find_next_packet drivers/media/dvb-core/dvb_demux.c:528 [inline] BUG: KASAN: slab-out-of-bounds in _dvb_dmx_swfilter drivers/media/dvb-core/dvb_demux.c:572 [inline] BUG: KASAN: slab-out-of-bounds in dvb_dmx_swfilter+0x3fa/0x420 drivers/media/dvb-core/dvb_demux.c:603 Read of size 1 at addr ffff8880608c00a0 by task swapper/2/0 CPU: 2 PID: 0 Comm: swapper/2 Not tainted 4.19.177-gdba4159c14ef #25 Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.12.0-59-gc9ba5276e321-prebuilt.qemu.org 04/01/2014 Call Trace: <IRQ> __dump_stack lib/dump_stack.c:77 [inline] dump_stack+0xec/0x156 lib/dump_stack.c:118 print_address_description+0x78/0x290 mm/kasan/report.c:256 kasan_report_error mm/kasan/report.c:354 [inline] kasan_report+0x25b/0x380 mm/kasan/report.c:412 __asan_report_load1_noabort+0x19/0x20 mm/kasan/report.c:430 find_next_packet drivers/media/dvb-core/dvb_demux.c:528 [inline] _dvb_dmx_swfilter drivers/media/dvb-core/dvb_demux.c:572 [inline] dvb_dmx_swfilter+0x3fa/0x420 drivers/media/dvb-core/dvb_demux.c:603 flexcop_pass_dmx_data+0x2e/0x40 drivers/media/common/b2c2/flexcop.c:167 flexcop_pci_isr+0x3d1/0x5d0 drivers/media/pci/b2c2/flexcop-pci.c:212 __handle_irq_event_percpu+0xfb/0x770 kernel/irq/handle.c:149 handle_irq_event_percpu+0x79/0x150 kernel/irq/handle.c:189 handle_irq_event+0xac/0x140 kernel/irq/handle.c:206 handle_fasteoi_irq+0x232/0x5c0 kernel/irq/chip.c:725 generic_handle_irq_desc include/linux/irqdesc.h:155 [inline] handle_irq+0x230/0x3a0 arch/x86/kernel/irq_64.c:87 do_IRQ+0xa7/0x1e0 arch/x86/kernel/irq.c:247 common_interrupt+0xf/0xf arch/x86/entry/entry_64.S:670 </IRQ> RIP: 0010:native_safe_halt+0x28/0x30 arch/x86/include/asm/irqflags.h:61 Code: 00 00 55 be 04 00 00 00 48 c7 c7 00 62 2f 8c 48 89 e5 e8 fb 31 e8 f8 8b 05 75 4f 8e 03 85 c0 7e 07 0f 00 2d 8a 61 66 00 fb f4 <5d> c3 90 90 90 90 90 90 0f 1f 44 00 00 55 48 89 e5 41 57 41 56 41 RSP: 0018:ffff88806b71fcc8 EFLAGS: 00000246 ORIG_RAX: ffffffffffffffde RAX: 0000000000000000 RBX: ffffffff8bde44c8 RCX: ffffffff88a11285 RDX: 0000000000000000 RSI: 0000000000000004 RDI: ffffffff8c2f6200 RBP: ffff88806b71fcc8 R08: fffffbfff185ec40 R09: fffffbfff185ec40 R10: 0000000000000001 R11: fffffbfff185ec40 R12: 0000000000000002 R13: ffffffff8be9d6e0 R14: 0000000000000000 R15: 0000000000000000 arch_safe_halt arch/x86/include/asm/paravirt.h:94 [inline] default_idle+0x6f/0x360 arch/x86/kernel/process.c:557 arch_cpu_idle+0xf/0x20 arch/x86/kernel/process.c:548 default_idle_call+0x3b/0x60 kernel/sched/idle.c:93 cpuidle_idle_call kernel/sched/idle.c:153 [inline] do_idle+0x2ab/0x3c0 kernel/sched/idle.c:263 cpu_startup_entry+0xcb/0xe0 kernel/sched/idle.c:369 start_secondary+0x3b8/0x4e0 arch/x86/kernel/smpboot.c:271 secondary_startup_64+0xa4/0xb0 arch/x86/kernel/head_64.S:243 Allocated by task 1: save_stack+0x43/0xd0 mm/kasan/kasan.c:448 set_track mm/kasan/kasan.c:460 [inline] kasan_kmalloc+0xad/0xe0 mm/kasan/kasan.c:553 kasan_slab_alloc+0x11/0x20 mm/kasan/kasan.c:490 slab_post_alloc_hook mm/slab.h:445 [inline] slab_alloc_node mm/slub.c:2741 [inline] slab_alloc mm/slub.c:2749 [inline] kmem_cache_alloc+0xeb/0x280 mm/slub.c:2754 kmem_cache_zalloc include/linux/slab.h:699 [inline] __kernfs_new_node+0xe2/0x6f0 fs/kernfs/dir.c:633 kernfs_new_node+0x9a/0x120 fs/kernfs/dir.c:693 __kernfs_create_file+0x5f/0x340 fs/kernfs/file.c:992 sysfs_add_file_mode_ns+0x22a/0x4e0 fs/sysfs/file.c:306 create_files fs/sysfs/group.c:63 [inline] internal_create_group+0x34e/0xc30 fs/sysfs/group.c:147 sysfs_create_group fs/sysfs/group.c:173 [inline] sysfs_create_groups+0x9c/0x140 fs/sysfs/group.c:200 driver_add_groups+0x3e/0x50 drivers/base/driver.c:129 bus_add_driver+0x3a5/0x790 drivers/base/bus.c:684 driver_register+0x1cd/0x410 drivers/base/driver.c:170 __pci_register_driver+0x197/0x200 drivers/pci/pci-driver.c:1411 cx88_audio_pci_driver_init+0x23/0x25 drivers/media/pci/cx88/cx88-alsa.c: 1017 do_one_initcall+0xe0/0x610 init/main.c:884 do_initcall_level init/main.c:952 [inline] do_initcalls init/main.c:960 [inline] do_basic_setup init/main.c:978 [inline] kernel_init_freeable+0x4d0/0x592 init/main.c:1145 kernel_init+0x18/0x190 init/main.c:1062 ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:415 Freed by task 0: (stack is not available) The buggy address belongs to the object at ffff8880608c0000 which belongs to the cache kernfs_node_cache of size 160 The buggy address is located 0 bytes to the right of 160-byte region [ffff8880608c0000, ffff8880608c00a0) The buggy address belongs to the page: page:ffffea0001823000 count:1 mapcount:0 mapping:ffff88806bed1e00 index:0x0 compound_mapcount: 0 flags: 0x100000000008100(slab|head) raw: 0100000000008100 dead000000000100 dead000000000200 ffff88806bed1e00 raw: 0000000000000000 0000000000240024 00000001ffffffff 0000000000000000 page dumped because: kasan: bad access detected Memory state around the buggy address: ffff8880608bff80: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ffff8880608c0000: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 >ffff8880608c0080: 00 00 00 00 fc fc fc fc fc fc fc fc 00 00 00 00 ^ ffff8880608c0100: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ffff8880608c0180: fc fc fc fc fc fc fc fc 00 00 00 00 00 00 00 00 ================================================================== Link: https://lore.kernel.org/linux-media/1620723603-30912-1-git-send-email-zheyuma97@gmail.com Reported-by: Zheyu Ma <zheyuma97@gmail.com> Signed-off-by: Zheyu Ma <zheyuma97@gmail.com> Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>
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