On 10. 08. 20, 9:51, Greg Kroah-Hartman wrote: > On Mon, Aug 10, 2020 at 07:16:48AM +0200, Jiri Slaby wrote: >> On 10. 08. 20, 0:14, James Bond wrote: >>> Syzkaller find a memory leak in con_insert_unipair: >>> BUG: memory leak >>> unreferenced object 0xffff88804893d100 (size 256): >>> comm "syz-executor.3", pid 16154, jiffies 4295043307 (age 2392.340s) >>> hex dump (first 32 bytes): >>> 80 af 88 4e 80 88 ff ff 00 a8 88 4e 80 88 ff ff ...N.......N.... >>> 80 ad 88 4e 80 88 ff ff 00 aa 88 4e 80 88 ff ff ...N.......N.... >>> backtrace: >>> [<00000000f76ff1de>] kmalloc include/linux/slab.h:555 [inline] >>> [<00000000f76ff1de>] kmalloc_array include/linux/slab.h:596 [inline] >>> [<00000000f76ff1de>] con_insert_unipair+0x9e/0x1a0 >>> drivers/tty/vt/consolemap.c:482 >>> [<000000002f1ad7da>] con_set_unimap+0x244/0x2a0 >>> drivers/tty/vt/consolemap.c:595 >>> [<0000000046ccb106>] do_unimap_ioctl drivers/tty/vt/vt_ioctl.c:297 >>> [inline] >>> [<0000000046ccb106>] vt_ioctl+0x863/0x12f0 >>> drivers/tty/vt/vt_ioctl.c:1018 >>> [<00000000db1577ff>] tty_ioctl+0x4cd/0xa30 drivers/tty/tty_io.c:2656 >>> [<00000000e5cdf5ed>] vfs_ioctl fs/ioctl.c:48 [inline] >>> [<00000000e5cdf5ed>] ksys_ioctl+0xa6/0xd0 fs/ioctl.c:753 >>> [<00000000fb4aa12c>] __do_sys_ioctl fs/ioctl.c:762 [inline] >>> [<00000000fb4aa12c>] __se_sys_ioctl fs/ioctl.c:760 [inline] >>> [<00000000fb4aa12c>] __x64_sys_ioctl+0x1a/0x20 fs/ioctl.c:760 >>> [<00000000f561f260>] do_syscall_64+0x4c/0xe0 arch/x86/entry/common.c:384 >>> [<0000000056206928>] entry_SYSCALL_64_after_hwframe+0x44/0xa9 >>> BUG: leak checking failed >>> >>> To fix this issue, we need to release the pointer p1 when the call of >>> the function kmalloc_array fail. ... >> Do we have some annotations for this instead? > > We need something there, a comment saying "this is fine, don't touch > it!" or something like that? We need that in a few other places in the > vt code as well.
Sure, comment as the last resort (to silence patch writers). But I had some kmemleak annotation (to silence the warning) in mind. Or better fix/tune kmemleak: why it dares to think it's a mem leak in the first place? thanks, -- js
