| From bippy-5f407fcff5a0 Mon Sep 17 00:00:00 2001 |
| From: Greg Kroah-Hartman <gregkh@linuxfoundation.org> |
| To: <linux-cve-announce@vger.kernel.org> |
| Reply-to: <cve@kernel.org>, <linux-kernel@vger.kernel.org> |
| Subject: CVE-2024-43910: bpf: add missing check_func_arg_reg_off() to prevent out-of-bounds memory accesses |
| |
| Description |
| =========== |
| |
| In the Linux kernel, the following vulnerability has been resolved: |
| |
| bpf: add missing check_func_arg_reg_off() to prevent out-of-bounds memory accesses |
| |
| Currently, it's possible to pass in a modified CONST_PTR_TO_DYNPTR to |
| a global function as an argument. The adverse effects of this is that |
| BPF helpers can continue to make use of this modified |
| CONST_PTR_TO_DYNPTR from within the context of the global function, |
| which can unintentionally result in out-of-bounds memory accesses and |
| therefore compromise overall system stability i.e. |
| |
| [ 244.157771] BUG: KASAN: slab-out-of-bounds in bpf_dynptr_data+0x137/0x140 |
| [ 244.161345] Read of size 8 at addr ffff88810914be68 by task test_progs/302 |
| [ 244.167151] CPU: 0 PID: 302 Comm: test_progs Tainted: G O E 6.10.0-rc3-00131-g66b586715063 #533 |
| [ 244.174318] Call Trace: |
| [ 244.175787] <TASK> |
| [ 244.177356] dump_stack_lvl+0x66/0xa0 |
| [ 244.179531] print_report+0xce/0x670 |
| [ 244.182314] ? __virt_addr_valid+0x200/0x3e0 |
| [ 244.184908] kasan_report+0xd7/0x110 |
| [ 244.187408] ? bpf_dynptr_data+0x137/0x140 |
| [ 244.189714] ? bpf_dynptr_data+0x137/0x140 |
| [ 244.192020] bpf_dynptr_data+0x137/0x140 |
| [ 244.194264] bpf_prog_b02a02fdd2bdc5fa_global_call_bpf_dynptr_data+0x22/0x26 |
| [ 244.198044] bpf_prog_b0fe7b9d7dc3abde_callback_adjust_bpf_dynptr_reg_off+0x1f/0x23 |
| [ 244.202136] bpf_user_ringbuf_drain+0x2c7/0x570 |
| [ 244.204744] ? 0xffffffffc0009e58 |
| [ 244.206593] ? __pfx_bpf_user_ringbuf_drain+0x10/0x10 |
| [ 244.209795] bpf_prog_33ab33f6a804ba2d_user_ringbuf_callback_const_ptr_to_dynptr_reg_off+0x47/0x4b |
| [ 244.215922] bpf_trampoline_6442502480+0x43/0xe3 |
| [ 244.218691] __x64_sys_prlimit64+0x9/0xf0 |
| [ 244.220912] do_syscall_64+0xc1/0x1d0 |
| [ 244.223043] entry_SYSCALL_64_after_hwframe+0x77/0x7f |
| [ 244.226458] RIP: 0033:0x7ffa3eb8f059 |
| [ 244.228582] Code: 08 89 e8 5b 5d c3 66 2e 0f 1f 84 00 00 00 00 00 90 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 8b 0d 8f 1d 0d 00 f7 d8 64 89 01 48 |
| [ 244.241307] RSP: 002b:00007ffa3e9c6eb8 EFLAGS: 00000206 ORIG_RAX: 000000000000012e |
| [ 244.246474] RAX: ffffffffffffffda RBX: 00007ffa3e9c7cdc RCX: 00007ffa3eb8f059 |
| [ 244.250478] RDX: 00007ffa3eb162b4 RSI: 0000000000000000 RDI: 00007ffa3e9c7fb0 |
| [ 244.255396] RBP: 00007ffa3e9c6ed0 R08: 00007ffa3e9c76c0 R09: 0000000000000000 |
| [ 244.260195] R10: 0000000000000000 R11: 0000000000000206 R12: ffffffffffffff80 |
| [ 244.264201] R13: 000000000000001c R14: 00007ffc5d6b4260 R15: 00007ffa3e1c7000 |
| [ 244.268303] </TASK> |
| |
| Add a check_func_arg_reg_off() to the path in which the BPF verifier |
| verifies the arguments of global function arguments, specifically |
| those which take an argument of type ARG_PTR_TO_DYNPTR | |
| MEM_RDONLY. Also, process_dynptr_func() doesn't appear to perform any |
| explicit and strict type matching on the supplied register type, so |
| let's also enforce that a register either type PTR_TO_STACK or |
| CONST_PTR_TO_DYNPTR is by the caller. |
| |
| The Linux kernel CVE team has assigned CVE-2024-43910 to this issue. |
| |
| |
| Affected and fixed versions |
| =========================== |
| |
| Issue introduced in 6.8 with commit a64bfe618665ea9c722f922cba8c6e3234eac5ac and fixed in 6.10.5 with commit 13663a7c644bf1dedaf461d07252db5d76c8759a |
| Issue introduced in 6.8 with commit a64bfe618665ea9c722f922cba8c6e3234eac5ac and fixed in 6.11 with commit ec2b9a5e11e51fea1bb04c1e7e471952e887e874 |
| |
| Please see https://www.kernel.org for a full list of currently supported |
| kernel versions by the kernel community. |
| |
| Unaffected versions might change over time as fixes are backported to |
| older supported kernel versions. The official CVE entry at |
| https://cve.org/CVERecord/?id=CVE-2024-43910 |
| will be updated if fixes are backported, please check that for the most |
| up to date information about this issue. |
| |
| |
| Affected files |
| ============== |
| |
| The file(s) affected by this issue are: |
| kernel/bpf/verifier.c |
| |
| |
| Mitigation |
| ========== |
| |
| The Linux kernel CVE team recommends that you update to the latest |
| stable kernel version for this, and many other bugfixes. Individual |
| changes are never tested alone, but rather are part of a larger kernel |
| release. Cherry-picking individual commits is not recommended or |
| supported by the Linux kernel community at all. If however, updating to |
| the latest release is impossible, the individual changes to resolve this |
| issue can be found at these commits: |
| https://git.kernel.org/stable/c/13663a7c644bf1dedaf461d07252db5d76c8759a |
| https://git.kernel.org/stable/c/ec2b9a5e11e51fea1bb04c1e7e471952e887e874 |
