From 480edc08e788f4ea50e800cddc12da006f49e6de Mon Sep 17 00:00:00 2001 From: Eric Dumazet Date: Mon, 7 Oct 2019 15:43:01 -0700 Subject: [PATCH] bonding: fix potential NULL deref in bond_update_slave_arr commit a7137534b597b7c303203e6bc3ed87e87a273bb8 upstream. syzbot got a NULL dereference in bond_update_slave_arr() [1], happening after a failure to allocate bond->slave_arr A workqueue (bond_slave_arr_handler) is supposed to retry the allocation later, but if the slave is removed before the workqueue had a chance to complete, bond->slave_arr can still be NULL. [1] Failed to build slave-array. kasan: CONFIG_KASAN_INLINE enabled kasan: GPF could be caused by NULL-ptr deref or user memory access general protection fault: 0000 [#1] SMP KASAN PTI Modules linked in: Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 RIP: 0010:bond_update_slave_arr.cold+0xc6/0x198 drivers/net/bonding/bond_main.c:4039 RSP: 0018:ffff88018fe33678 EFLAGS: 00010246 RAX: dffffc0000000000 RBX: 0000000000000000 RCX: ffffc9000290b000 RDX: 0000000000000000 RSI: ffffffff82b63037 RDI: ffff88019745ea20 RBP: ffff88018fe33760 R08: ffff880170754280 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000000 R12: 0000000000000000 R13: ffff88019745ea00 R14: 0000000000000000 R15: ffff88018fe338b0 FS: 00007febd837d700(0000) GS:ffff8801dad00000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00000000004540a0 CR3: 00000001c242e005 CR4: 00000000001626f0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 Call Trace: [] __bond_release_one+0x43e/0x500 drivers/net/bonding/bond_main.c:1923 [] bond_release drivers/net/bonding/bond_main.c:2039 [inline] [] bond_do_ioctl+0x416/0x870 drivers/net/bonding/bond_main.c:3562 [] dev_ifsioc+0x6f4/0x940 net/core/dev_ioctl.c:328 [] dev_ioctl+0x1b8/0xc70 net/core/dev_ioctl.c:495 [] sock_do_ioctl+0x1bd/0x300 net/socket.c:1088 [] sock_ioctl+0x300/0x5d0 net/socket.c:1196 [] vfs_ioctl fs/ioctl.c:47 [inline] [] file_ioctl fs/ioctl.c:501 [inline] [] do_vfs_ioctl+0xacb/0x1300 fs/ioctl.c:688 [] SYSC_ioctl fs/ioctl.c:705 [inline] [] SyS_ioctl+0xb6/0xe0 fs/ioctl.c:696 [] do_syscall_64+0x528/0x770 arch/x86/entry/common.c:305 [] entry_SYSCALL_64_after_hwframe+0x42/0xb7 Fixes: ee6377147409 ("bonding: Simplify the xmit function for modes that use xmit_hash") Signed-off-by: Eric Dumazet Reported-by: syzbot Cc: Mahesh Bandewar Signed-off-by: Jakub Kicinski Signed-off-by: Greg Kroah-Hartman --- drivers/net/bonding/bond_main.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/drivers/net/bonding/bond_main.c b/drivers/net/bonding/bond_main.c index 8820fb1aec5b..c1971bca62fb 100644 --- a/drivers/net/bonding/bond_main.c +++ b/drivers/net/bonding/bond_main.c @@ -3963,7 +3963,7 @@ int bond_update_slave_arr(struct bonding *bond, struct slave *skipslave) * this to-be-skipped slave to send a packet out. */ old_arr = rtnl_dereference(bond->slave_arr); - for (idx = 0; idx < old_arr->count; idx++) { + for (idx = 0; old_arr != NULL && idx < old_arr->count; idx++) { if (skipslave == old_arr->arr[idx]) { old_arr->arr[idx] = old_arr->arr[old_arr->count-1];