• Jouni Hogander's avatar
    can: slcan: Fix use-after-free Read in slcan_open · 9ebd796e
    Jouni Hogander authored
    Slcan_open doesn't clean-up device which registration failed from the
    slcan_devs device list. On next open this list is iterated and freed
    device is accessed. Fix this by calling slc_free_netdev in error path.
    
    Driver/net/can/slcan.c is derived from slip.c. Use-after-free error was
    identified in slip_open by syzboz. Same bug is in slcan.c. Here is the
    trace from the Syzbot slip report:
    
    __dump_stack lib/dump_stack.c:77 [inline]
    dump_stack+0x197/0x210 lib/dump_stack.c:118
    print_address_description.constprop.0.cold+0xd4/0x30b mm/kasan/report.c:374
    __kasan_report.cold+0x1b/0x41 mm/kasan/report.c:506
    kasan_report+0x12/0x20 mm/kasan/common.c:634
    __asan_report_load8_noabort+0x14/0x20 mm/kasan/generic_report.c:132
    sl_sync drivers/net/slip/slip.c:725 [inline]
    slip_open+0xecd/0x11b7 drivers/net/slip/slip.c:801
    tty_ldisc_open.isra.0+0xa3/0x110 drivers/tty/tty_ldisc.c:469
    tty_set_ldisc+0x30e/0x6b0 drivers/tty/tty_ldisc.c:596
    tiocsetd drivers/tty/tty_io.c:2334 [inline]
    tty_ioctl+0xe8d/0x14f0 drivers/tty/tty_io.c:2594
    vfs_ioctl fs/ioctl.c:46 [inline]
    file_ioctl fs/ioctl.c:509 [inline]
    do_vfs_ioctl+0xdb6/0x13e0 fs/ioctl.c:696
    ksys_ioctl+0xab/0xd0 fs/ioctl.c:713
    __do_sys_ioctl fs/ioctl.c:720 [inline]
    __se_sys_ioctl fs/ioctl.c:718 [inline]
    __x64_sys_ioctl+0x73/0xb0 fs/ioctl.c:718
    do_syscall_64+0xfa/0x760 arch/x86/entry/common.c:290
    entry_SYSCALL_64_after_hwframe+0x49/0xbe
    
    Fixes: ed50e160 ("slcan: Fix memory leak in error path")
    Cc: Wolfgang Grandegger <wg@grandegger.com>
    Cc: Marc Kleine-Budde <mkl@pengutronix.de>
    Cc: David Miller <davem@davemloft.net>
    Cc: Oliver Hartkopp <socketcan@hartkopp.net>
    Cc: Lukas Bulwahn <lukas.bulwahn@gmail.com>
    Signed-off-by: default avatarJouni Hogander <jouni.hogander@unikie.com>
    Cc: linux-stable <stable@vger.kernel.org> # >= v5.4
    Acked-by: default avatarOliver Hartkopp <socketcan@hartkopp.net>
    Signed-off-by: default avatarMarc Kleine-Budde <mkl@pengutronix.de>
    9ebd796e
slcan.c 19.7 KB