CVE-2024-46763

In the Linux kernel, the following vulnerability has been resolved: fou: Fix null-ptr-deref in GRO. We observed a null-ptr-deref in fou_gro_receive() while shutting down a host. [0] The NULL pointer is sk->sk_user_data, and the offset 8 is of protocol in struct fou. When fou_release() is called due to netns dismantle or explicit tunnel teardown, udp_tunnel_sock_release() sets NULL to sk->sk_user_data. Then, the tunnel socket is destroyed after a single RCU grace period. So, in-flight udp4_gro_receive() could find the socket and execute the FOU GRO handler, where sk->sk_user_data could be NULL. Let's use rcu_dereference_sk_user_data() in fou_from_sock() and add NULL checks in FOU GRO handlers. [0]: BUG: kernel NULL pointer dereference, address: 0000000000000008 PF: supervisor read access in kernel mode PF: error_code(0x0000) - not-present page PGD 80000001032f4067 P4D 80000001032f4067 PUD 103240067 PMD 0 SMP PTI CPU: 0 PID: 0 Comm: swapper/0 Not tainted 5.10.216-204.855.amzn2.x86_64 #1 Hardware name: Amazon EC2 c5.large/, BIOS 1.0 10/16/2017 RIP: 0010:fou_gro_receive (net/ipv4/fou.c:233) [fou] Code: 41 5f c3 cc cc cc cc e8 e7 2e 69 f4 0f 1f 80 00 00 00 00 0f 1f 44 00 00 49 89 f8 41 54 48 89 f7 48 89 d6 49 8b 80 88 02 00 00 <0f> b6 48 08 0f b7 42 4a 66 25 fd fd 80 cc 02 66 89 42 4a 0f b6 42 RSP: 0018:ffffa330c0003d08 EFLAGS: 00010297 RAX: 0000000000000000 RBX: ffff93d9e3a6b900 RCX: 0000000000000010 RDX: ffff93d9e3a6b900 RSI: ffff93d9e3a6b900 RDI: ffff93dac2e24d08 RBP: ffff93d9e3a6b900 R08: ffff93dacbce6400 R09: 0000000000000002 R10: 0000000000000000 R11: ffffffffb5f369b0 R12: ffff93dacbce6400 R13: ffff93dac2e24d08 R14: 0000000000000000 R15: ffffffffb4edd1c0 FS: 0000000000000000(0000) GS:ffff93daee800000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 0000000000000008 CR3: 0000000102140001 CR4: 00000000007706f0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 PKRU: 55555554 Call Trace: <IRQ> ? show_trace_log_lvl (arch/x86/kernel/dumpstack.c:259) ? __die_body.cold (arch/x86/kernel/dumpstack.c:478 arch/x86/kernel/dumpstack.c:420) ? no_context (arch/x86/mm/fault.c:752) ? exc_page_fault (arch/x86/include/asm/irqflags.h:49 arch/x86/include/asm/irqflags.h:89 arch/x86/mm/fault.c:1435 arch/x86/mm/fault.c:1483) ? asm_exc_page_fault (arch/x86/include/asm/idtentry.h:571) ? fou_gro_receive (net/ipv4/fou.c:233) [fou] udp_gro_receive (include/linux/netdevice.h:2552 net/ipv4/udp_offload.c:559) udp4_gro_receive (net/ipv4/udp_offload.c:604) inet_gro_receive (net/ipv4/af_inet.c:1549 (discriminator 7)) dev_gro_receive (net/core/dev.c:6035 (discriminator 4)) napi_gro_receive (net/core/dev.c:6170) ena_clean_rx_irq (drivers/amazon/net/ena/ena_netdev.c:1558) [ena] ena_io_poll (drivers/amazon/net/ena/ena_netdev.c:1742) [ena] napi_poll (net/core/dev.c:6847) net_rx_action (net/core/dev.c:6917) __do_softirq (arch/x86/include/asm/jump_label.h:25 include/linux/jump_label.h:200 include/trace/events/irq.h:142 kernel/softirq.c:299) asm_call_irq_on_stack (arch/x86/entry/entry_64.S:809) </IRQ> do_softirq_own_stack (arch/x86/include/asm/irq_stack.h:27 arch/x86/include/asm/irq_stack.h:77 arch/x86/kernel/irq_64.c:77) irq_exit_rcu (kernel/softirq.c:393 kernel/softirq.c:423 kernel/softirq.c:435) common_interrupt (arch/x86/kernel/irq.c:239) asm_common_interrupt (arch/x86/include/asm/idtentry.h:626) RIP: 0010:acpi_idle_do_entry (arch/x86/include/asm/irqflags.h:49 arch/x86/include/asm/irqflags.h:89 drivers/acpi/processor_idle.c:114 drivers/acpi/processor_idle.c:575) Code: 8b 15 d1 3c c4 02 ed c3 cc cc cc cc 65 48 8b 04 25 40 ef 01 00 48 8b 00 a8 08 75 eb 0f 1f 44 00 00 0f 00 2d d5 09 55 00 fb f4 <fa> c3 cc cc cc cc e9 be fc ff ff 66 66 2e 0f 1f 84 00 00 00 00 00 RSP: 0018:ffffffffb5603e58 EFLAGS: 00000246 RAX: 0000000000004000 RBX: ffff93dac0929c00 RCX: ffff93daee833900 RDX: ffff93daee800000 RSI: ffff93d ---truncated---

It was discovered that the CIFS network file system implementation in the Linux kernel did not properly validate certain SMB messages, leading to an out-of-bounds read vulnerability. An attacker could use this to cause a denial of service or possibly expose sensitive information. Supraja Sridhara, Benedict Schlüter, Mark Kuhne, Andrin Bertschi, and Shweta Shinde discovered that the Confidential Computing framework in the Linux kernel for x86 platforms did not properly handle 32-bit emulation on TDX and SEV. An attacker with access to the VMM could use this to cause a denial of service or possibly execute arbitrary code.