From: Eric Dumazet edumazet@google.com
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: [<ffffffff82b5b45e>] __bond_release_one+0x43e/0x500 drivers/net/bonding/bond_main.c:1923 [<ffffffff82b5b966>] bond_release drivers/net/bonding/bond_main.c:2039 [inline] [<ffffffff82b5b966>] bond_do_ioctl+0x416/0x870 drivers/net/bonding/bond_main.c:3562 [<ffffffff83ae25f4>] dev_ifsioc+0x6f4/0x940 net/core/dev_ioctl.c:328 [<ffffffff83ae2e58>] dev_ioctl+0x1b8/0xc70 net/core/dev_ioctl.c:495 [<ffffffff83995ffd>] sock_do_ioctl+0x1bd/0x300 net/socket.c:1088 [<ffffffff83996a80>] sock_ioctl+0x300/0x5d0 net/socket.c:1196 [<ffffffff81b124db>] vfs_ioctl fs/ioctl.c:47 [inline] [<ffffffff81b124db>] file_ioctl fs/ioctl.c:501 [inline] [<ffffffff81b124db>] do_vfs_ioctl+0xacb/0x1300 fs/ioctl.c:688 [<ffffffff81b12dc6>] SYSC_ioctl fs/ioctl.c:705 [inline] [<ffffffff81b12dc6>] SyS_ioctl+0xb6/0xe0 fs/ioctl.c:696 [<ffffffff8101ccc8>] do_syscall_64+0x528/0x770 arch/x86/entry/common.c:305 [<ffffffff84400091>] 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 edumazet@google.com Reported-by: syzbot syzkaller@googlegroups.com Cc: Mahesh Bandewar maheshb@google.com Signed-off-by: Jakub Kicinski jakub.kicinski@netronome.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org
--- drivers/net/bonding/bond_main.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)
--- a/drivers/net/bonding/bond_main.c +++ b/drivers/net/bonding/bond_main.c @@ -4039,7 +4039,7 @@ out: * 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];