Messages in this thread | | | Date | Fri, 10 Aug 2018 07:36:04 +0200 | From | Steffen Klassert <> | Subject | Re: [BUG] net: xfrm: Two possible sleep-in-atomic-context bugs |
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On Fri, Aug 10, 2018 at 10:02:42AM +0800, bai wrote: > The code may sleep in interrupt handler. > xfrm_trans_reinject() is an interrupt handler set in tasklet_init(). > The function call paths (from bottom to top) in Linux-4.16 are: > > [FUNC] schedule_timeout > net/core/sock.c, 2044: schedule_timeout in sock_wait_for_wmem > net/core/sock.c, 2083: sock_wait_for_wmem in sock_alloc_send_pskb > net/core/sock.c, 2102: sock_alloc_send_pskb in sock_alloc_send_skb > net/ipv6/mcast.c, 1989: sock_alloc_send_skb in igmp6_send
igmp6_send calls sock_alloc_send_skb with 'noblock = 1', this means that sock_wait_for_wmem is not executed in sock_alloc_send_pskb.
> net/ipv6/mcast.c, 2391: igmp6_send in igmp6_join_group > net/ipv6/mcast.c, 670: igmp6_join_group in igmp6_group_added > net/ipv6/mcast.c, 914: igmp6_group_added in ipv6_dev_mc_inc > net/ipv6/ndisc.c, 379: ipv6_dev_mc_inc in pndisc_constructor > net/core/neighbour.c, 640: [FUNC_PTR]pndisc_constructor in pneigh_lookup > net/ipv6/ip6_output.c, 483: pneigh_lookup in ip6_forward > ./include/net/dst.h, 449: [FUNC_PTR]ip6_forward in dst_input > net/ipv6/ip6_input.c, 71: dst_input in ip6_rcv_finish > net/xfrm/xfrm_input.c, 511: [FUNC_PTR]ip6_rcv_finish in xfrm_trans_reinject > > [FUNC] kmalloc(GFP_KERNEL) > net/core/neighbour.c, 630: kmalloc in pneigh_lookup > net/ipv6/ip6_output.c, 483: pneigh_lookup in ip6_forward
ip6_forward calls pneigh_lookup with 'creat = 0', this means that pneigh_lookup does not do the kmalloc.
> ./include/net/dst.h, 449: [FUNC_PTR]ip6_forward in dst_input > net/ipv6/ip6_input.c, 71: dst_input in ip6_rcv_finish > net/xfrm/xfrm_input.c, 511: [FUNC_PTR]ip6_rcv_finish in xfrm_trans_reinject > > Note that [FUNC_PTR] means a function pointer call is used. > > I do not find a good way to fix them, so I only report. > These possible bugs are found by my static analysis tool (DSAC) and checked > by my code review.
Both codepaths are ok, maybe you should fix your tool ;-)
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