CVE-2024-44989: bonding: fix xfrm real_dev null pointer dereference

In the Linux kernel, the following vulnerability has been resolved:

bonding: fix xfrm realdev null pointer dereference

We shouldn't set realdev to NULL because packets can be in transit and xfrm might call xdodevoffloadok() in parallel. All callbacks assume realdev is set.

Example trace: kernel: BUG: unable to handle page fault for address: 0000000000001030 kernel: bond0: (slave eni0np1): making interface the new active one kernel: #PF: supervisor write access in kernel mode kernel: #PF: errorcode(0x0002) - not-present page kernel: PGD 0 P4D 0 kernel: Oops: 0002 [#1] PREEMPT SMP kernel: CPU: 4 PID: 2237 Comm: ping Not tainted 6.7.7+ #12 kernel: Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.3-2.fc40 04/01/2014 kernel: RIP: 0010:nsimipsecoffloadok+0xc/0x20 [netdevsim] kernel: bond0: (slave eni0np1): bondipsecaddsaall: failed to add SA kernel: Code: e0 0f 0b 48 83 7f 38 00 74 de 0f 0b 48 8b 47 08 48 8b 37 48 8b 78 40 e9 b2 e5 9a d7 66 90 0f 1f 44 00 00 48 8b 86 80 02 00 00 <83> 80 30 10 00 00 01 b8 01 00 00 00 c3 0f 1f 80 00 00 00 00 0f 1f kernel: bond0: (slave eni0np1): making interface the new active one kernel: RSP: 0018:ffffabde81553b98 EFLAGS: 00010246 kernel: bond0: (slave eni0np1): bondipsecaddsaall: failed to add SA kernel: kernel: RAX: 0000000000000000 RBX: ffff9eb404e74900 RCX: ffff9eb403d97c60 kernel: RDX: ffffffffc090de10 RSI: ffff9eb404e74900 RDI: ffff9eb3c5de9e00 kernel: RBP: ffff9eb3c0a42000 R08: 0000000000000010 R09: 0000000000000014 kernel: R10: 7974203030303030 R11: 3030303030303030 R12: 0000000000000000 kernel: R13: ffff9eb3c5de9e00 R14: ffffabde81553cc8 R15: ffff9eb404c53000 kernel: FS: 00007f2a77a3ad00(0000) GS:ffff9eb43bd00000(0000) knlGS:0000000000000000 kernel: CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 kernel: CR2: 0000000000001030 CR3: 00000001122ab000 CR4: 0000000000350ef0 kernel: bond0: (slave eni0np1): making interface the new active one kernel: Call Trace: kernel: <TASK> kernel: ? die+0x1f/0x60 kernel: bond0: (slave eni0np1): bondipsecaddsaall: failed to add SA kernel: ? pagefaultoops+0x142/0x4c0 kernel: ? douseraddrfault+0x65/0x670 kernel: ? kvmreadandresetapfflags+0x3b/0x50 kernel: bond0: (slave eni0np1): making interface the new active one kernel: ? excpagefault+0x7b/0x180 kernel: ? asmexcpagefault+0x22/0x30 kernel: ? nsimbpfuninit+0x50/0x50 [netdevsim] kernel: bond0: (slave eni0np1): bondipsecaddsaall: failed to add SA kernel: ? nsimipsecoffloadok+0xc/0x20 [netdevsim] kernel: bond0: (slave eni0np1): making interface the new active one kernel: bondipsecoffloadok+0x7b/0x90 [bonding] kernel: xfrmoutput+0x61/0x3b0 kernel: bond0: (slave eni0np1): bondipsecaddsaall: failed to add SA kernel: ippushpendingframes+0x56/0x80

— NVD