Em Thu, 10 Oct 2024 20:06:29 -0500 Chenyuan Yang <chenyuan0y@xxxxxxxxx> escreveu: > Dear Linux Developers for DVB, > > I am writing to inquire if there have been any updates regarding the > memory leak issue. The issue remains reproducible on the latest stable > Linux version (6.12-rc2, commit > 8cf0b93919e13d1e8d4466eb4080a4c4d9d66d7b). The DVB demux has internally a state machine to filter MPEG-TS streams. It needs to allocate data and buffers when setting such filters. So, the ioctls described at https://www.kernel.org/doc/html/v4.10/media/uapi/dvb/dmx_fcalls.html work together. Having a report that calling DMX functions on a fuzz testing result on memory keeping allocated sounds a normal behavior to me, as such filters are meant to be persistent. I need to double-check, but I'm almost sure this is persistent even after device close(). So, de-allocation should happen when the device driver is removed or when a new set of filters is set. In the last case, the old buffers will be freed and a new set of buffers will be allocated. > > Thank you for your attention to this matter. > > Best, > Chenyuan > > On Sat, Mar 2, 2024 at 3:12 PM Chenyuan Yang <chenyuan0y@xxxxxxxxx> wrote: > > > > Dear Linux Developers for DVB, > > > > We encountered "memory leak in dvb_dmxdev_add_pid" when testing the > > DVB driver with Syzkaller and our generated specifications. > > > > The C reproducer and the config for the kernel are attached. > > > > The memory leak originates from the allocated dmxdev_feed structure, > > as referenced in the code at > > [https://elixir.bootlin.com/linux/latest/source/drivers/media/dvb-core/dmxdev.c#L881]. > > This structure fails to be freed upon entering the code branch found > > at [https://elixir.bootlin.com/linux/latest/source/drivers/media/dvb-core/dmxdev.c#L891]. > > > > ``` > > ioctl$KGPT_DMX_START(r0, 0x6f29, 0x0) > > BUG: memory leak > > unreferenced object 0xffff88802e9ae7e0 (size 32): > > comm "syz-executor.0", pid 27777, jiffies 4295115050 (age 15.550s) > > hex dump (first 32 bytes): > > 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................ > > 08 c0 6a 05 00 c9 ff ff 08 c0 6a 05 00 c9 ff ff ..j.......j..... > > backtrace: > > [<ffffffff8169126f>] kmemleak_alloc_recursive > > scratch/zijie-data/LLM-Kernel/spec-eval/shared_linux_builds/syzbot-leak-more_631373bc9e824969/./include/linux/kmemleak.h:42 > > [inline] > > [<ffffffff8169126f>] slab_post_alloc_hook > > scratch/zijie-data/LLM-Kernel/spec-eval/shared_linux_builds/syzbot-leak-more_631373bc9e824969/mm/slab.h:766 > > [inline] > > [<ffffffff8169126f>] slab_alloc_node > > scratch/zijie-data/LLM-Kernel/spec-eval/shared_linux_builds/syzbot-leak-more_631373bc9e824969/mm/slub.c:3478 > > [inline] > > [<ffffffff8169126f>] __kmem_cache_alloc_node+0x2ff/0x3e0 > > scratch/zijie-data/LLM-Kernel/spec-eval/shared_linux_builds/syzbot-leak-more_631373bc9e824969/mm/slub.c:3517 > > [<ffffffff815d9da9>] kmalloc_trace+0x29/0x90 > > scratch/zijie-data/LLM-Kernel/spec-eval/shared_linux_builds/syzbot-leak-more_631373bc9e824969/mm/slab_common.c:1098 > > [<ffffffff83db2e09>] kmalloc > > scratch/zijie-data/LLM-Kernel/spec-eval/shared_linux_builds/syzbot-leak-more_631373bc9e824969/./include/linux/slab.h:600 > > [inline] > > [<ffffffff83db2e09>] kzalloc > > scratch/zijie-data/LLM-Kernel/spec-eval/shared_linux_builds/syzbot-leak-more_631373bc9e824969/./include/linux/slab.h:721 > > [inline] > > [<ffffffff83db2e09>] dvb_dmxdev_add_pid+0xa9/0x160 > > scratch/zijie-data/LLM-Kernel/spec-eval/shared_linux_builds/syzbot-leak-more_631373bc9e824969/drivers/media/dvb-core/dmxdev.c:881 > > [<ffffffff83db48de>] dvb_dmxdev_pes_filter_set > > scratch/zijie-data/LLM-Kernel/spec-eval/shared_linux_builds/syzbot-leak-more_631373bc9e824969/drivers/media/dvb-core/dmxdev.c:956 > > [inline] > > [<ffffffff83db48de>] dvb_demux_do_ioctl+0x67e/0xa80 > > scratch/zijie-data/LLM-Kernel/spec-eval/shared_linux_builds/syzbot-leak-more_631373bc9e824969/drivers/media/dvb-core/dmxdev.c:1076 > > [<ffffffff83db1252>] dvb_usercopy+0x82/0x220 > > scratch/zijie-data/LLM-Kernel/spec-eval/shared_linux_builds/syzbot-leak-more_631373bc9e824969/drivers/media/dvb-core/dvbdev.c:986 > > [<ffffffff83db1b51>] dvb_demux_ioctl+0x31/0x40 > > scratch/zijie-data/LLM-Kernel/spec-eval/shared_linux_builds/syzbot-leak-more_631373bc9e824969/drivers/media/dvb-core/dmxdev.c:1185 > > [<ffffffff8171ca88>] vfs_ioctl > > scratch/zijie-data/LLM-Kernel/spec-eval/shared_linux_builds/syzbot-leak-more_631373bc9e824969/fs/ioctl.c:51 > > [inline] > > [<ffffffff8171ca88>] __do_sys_ioctl > > scratch/zijie-data/LLM-Kernel/spec-eval/shared_linux_builds/syzbot-leak-more_631373bc9e824969/fs/ioctl.c:871 > > [inline] > > [<ffffffff8171ca88>] __se_sys_ioctl > > scratch/zijie-data/LLM-Kernel/spec-eval/shared_linux_builds/syzbot-leak-more_631373bc9e824969/fs/ioctl.c:857 > > [inline] > > [<ffffffff8171ca88>] __x64_sys_ioctl+0x108/0x150 > > scratch/zijie-data/LLM-Kernel/spec-eval/shared_linux_builds/syzbot-leak-more_631373bc9e824969/fs/ioctl.c:857 > > [<ffffffff8540b150>] do_syscall_x64 > > scratch/zijie-data/LLM-Kernel/spec-eval/shared_linux_builds/syzbot-leak-more_631373bc9e824969/arch/x86/entry/common.c:51 > > [inline] > > [<ffffffff8540b150>] do_syscall_64+0x40/0x110 > > scratch/zijie-data/LLM-Kernel/spec-eval/shared_linux_builds/syzbot-leak-more_631373bc9e824969/arch/x86/entry/common.c:82 > > [<ffffffff8560008b>] entry_SYSCALL_64_after_hwframe+0x63/0x6b > > ``` > > > > If you have any questions or require more information, please feel > > free to contact us. > > > > Reported-by: Chenyuan Yang <chenyuan0y@xxxxxxxxx> > > > > Best, > > Chenyuan Thanks, Mauro
