3.16.76-rc1 review patch. If anyone has any objections, please let me know.
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From: Eric Dumazet edumazet@google.com
commit e5b1c6c6277d5a283290a8c033c72544746f9b5b upstream.
im->tomb and/or im->sources might not be NULL, but we currently overwrite their values blindly.
Using swap() will make sure the following call to kfree_pmc(pmc) will properly free the psf structures.
Tested with the C repro provided by syzbot, which basically does :
socket(PF_INET, SOCK_DGRAM, IPPROTO_IP) = 3 setsockopt(3, SOL_IP, IP_ADD_MEMBERSHIP, "\340\0\0\2\177\0\0\1\0\0\0\0", 12) = 0 ioctl(3, SIOCSIFFLAGS, {ifr_name="lo", ifr_flags=0}) = 0 setsockopt(3, SOL_IP, IP_MSFILTER, "\340\0\0\2\177\0\0\1\1\0\0\0\1\0\0\0\377\377\377\377", 20) = 0 ioctl(3, SIOCSIFFLAGS, {ifr_name="lo", ifr_flags=IFF_UP}) = 0 exit_group(0) = ?
BUG: memory leak unreferenced object 0xffff88811450f140 (size 64): comm "softirq", pid 0, jiffies 4294942448 (age 32.070s) hex dump (first 32 bytes): 00 00 00 00 00 00 00 00 ff ff ff ff 00 00 00 00 ................ 00 00 00 00 00 00 00 00 01 00 00 00 00 00 00 00 ................ backtrace: [<00000000c7bad083>] kmemleak_alloc_recursive include/linux/kmemleak.h:43 [inline] [<00000000c7bad083>] slab_post_alloc_hook mm/slab.h:439 [inline] [<00000000c7bad083>] slab_alloc mm/slab.c:3326 [inline] [<00000000c7bad083>] kmem_cache_alloc_trace+0x13d/0x280 mm/slab.c:3553 [<000000009acc4151>] kmalloc include/linux/slab.h:547 [inline] [<000000009acc4151>] kzalloc include/linux/slab.h:742 [inline] [<000000009acc4151>] ip_mc_add1_src net/ipv4/igmp.c:1976 [inline] [<000000009acc4151>] ip_mc_add_src+0x36b/0x400 net/ipv4/igmp.c:2100 [<000000004ac14566>] ip_mc_msfilter+0x22d/0x310 net/ipv4/igmp.c:2484 [<0000000052d8f995>] do_ip_setsockopt.isra.0+0x1795/0x1930 net/ipv4/ip_sockglue.c:959 [<000000004ee1e21f>] ip_setsockopt+0x3b/0xb0 net/ipv4/ip_sockglue.c:1248 [<0000000066cdfe74>] udp_setsockopt+0x4e/0x90 net/ipv4/udp.c:2618 [<000000009383a786>] sock_common_setsockopt+0x38/0x50 net/core/sock.c:3126 [<00000000d8ac0c94>] __sys_setsockopt+0x98/0x120 net/socket.c:2072 [<000000001b1e9666>] __do_sys_setsockopt net/socket.c:2083 [inline] [<000000001b1e9666>] __se_sys_setsockopt net/socket.c:2080 [inline] [<000000001b1e9666>] __x64_sys_setsockopt+0x26/0x30 net/socket.c:2080 [<00000000420d395e>] do_syscall_64+0x76/0x1a0 arch/x86/entry/common.c:301 [<000000007fd83a4b>] entry_SYSCALL_64_after_hwframe+0x44/0xa9
Fixes: 24803f38a5c0 ("igmp: do not remove igmp souce list info when set link down") Signed-off-by: Eric Dumazet edumazet@google.com Cc: Hangbin Liu liuhangbin@gmail.com Reported-by: syzbot+6ca1abd0db68b5173a4f@syzkaller.appspotmail.com Signed-off-by: David S. Miller davem@davemloft.net Signed-off-by: Ben Hutchings ben@decadent.org.uk --- net/ipv4/igmp.c | 8 ++------ 1 file changed, 2 insertions(+), 6 deletions(-)
--- a/net/ipv4/igmp.c +++ b/net/ipv4/igmp.c @@ -1178,12 +1178,8 @@ static void igmpv3_del_delrec(struct in_ im->interface = pmc->interface; im->crcount = in_dev->mr_qrv ?: IGMP_Unsolicited_Report_Count; if (im->sfmode == MCAST_INCLUDE) { - im->tomb = pmc->tomb; - pmc->tomb = NULL; - - im->sources = pmc->sources; - pmc->sources = NULL; - + swap(im->tomb, pmc->tomb); + swap(im->sources, pmc->sources); for (psf = im->sources; psf; psf = psf->sf_next) psf->sf_crcount = im->crcount; }