3.16.85-rc1 review patch. If anyone has any objections, please let me know.
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From: Jouni Hogander jouni.hogander@unikie.com
commit 9ebd796e24008f33f06ebea5a5e6aceb68b51794 upstream.
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: ed50e1600b44 ("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: Jouni Hogander jouni.hogander@unikie.com Acked-by: Oliver Hartkopp socketcan@hartkopp.net Signed-off-by: Marc Kleine-Budde mkl@pengutronix.de [bwh: Backported to 3.16: slc_free_netdev() calls free_netdev() here, so delete the direct call to free_netdev()] Signed-off-by: Ben Hutchings ben@decadent.org.uk --- --- a/drivers/net/can/slcan.c +++ b/drivers/net/can/slcan.c @@ -620,7 +620,7 @@ err_free_chan: sl->tty = NULL; tty->disc_data = NULL; clear_bit(SLF_INUSE, &sl->flags); - free_netdev(sl->dev); + slc_free_netdev(sl->dev);
err_exit: rtnl_unlock();