CVE-2024-26597

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

net: qualcomm: rmnet: fix global oob in rmnet_policy

The variable rmnet_link_ops assign a bigger maxtype which leads to a global out-of-bounds read when parsing the netlink attributes. See bug trace below:

================================================================== BUG: KASAN: global-out-of-bounds in validate_nla lib/nlattr.c:386 [inline] BUG: KASAN: global-out-of-bounds in __nla_validate_parse+0x24af/0x2750 lib/nlattr.c:600 Read of size 1 at addr ffffffff92c438d0 by task syz-executor.6/84207

CPU: 0 PID: 84207 Comm: syz-executor.6 Tainted: G N 6.1.0 #3 Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.13.0-1ubuntu1.1 04/01/2014 Call Trace: __dump_stack lib/dump_stack.c:88 [inline] dump_stack_lvl+0x8b/0xb3 lib/dump_stack.c:106 print_address_description mm/kasan/report.c:284 [inline] print_report+0x172/0x475 mm/kasan/report.c:395 kasan_report+0xbb/0x1c0 mm/kasan/report.c:495 validate_nla lib/nlattr.c:386 [inline] __nla_validate_parse+0x24af/0x2750 lib/nlattr.c:600 __nla_parse+0x3e/0x50 lib/nlattr.c:697 nla_parse_nested_deprecated include/net/netlink.h:1248 [inline] __rtnl_newlink+0x50a/0x1880 net/core/rtnetlink.c:3485 rtnl_newlink+0x64/0xa0 net/core/rtnetlink.c:3594 rtnetlink_rcv_msg+0x43c/0xd70 net/core/rtnetlink.c:6091 netlink_rcv_skb+0x14f/0x410 net/netlink/af_netlink.c:2540 netlink_unicast_kernel net/netlink/af_netlink.c:1319 [inline] netlink_unicast+0x54e/0x800 net/netlink/af_netlink.c:1345 netlink_sendmsg+0x930/0xe50 net/netlink/af_netlink.c:1921 sock_sendmsg_nosec net/socket.c:714 [inline] sock_sendmsg+0x154/0x190 net/socket.c:734 ____sys_sendmsg+0x6df/0x840 net/socket.c:2482 ___sys_sendmsg+0x110/0x1b0 net/socket.c:2536 __sys_sendmsg+0xf3/0x1c0 net/socket.c:2565 do_syscall_x64 arch/x86/entry/common.c:50 [inline] do_syscall_64+0x3b/0x90 arch/x86/entry/common.c:80 entry_SYSCALL_64_after_hwframe+0x63/0xcd RIP: 0033:0x7fdcf2072359 Code: 28 00 00 00 75 05 48 83 c4 28 c3 e8 f1 19 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 c7 c1 b8 ff ff ff f7 d8 64 89 01 48 RSP: 002b:00007fdcf13e3168 EFLAGS: 00000246 ORIG_RAX: 000000000000002e RAX: ffffffffffffffda RBX: 00007fdcf219ff80 RCX: 00007fdcf2072359 RDX: 0000000000000000 RSI: 0000000020000200 RDI: 0000000000000003 RBP: 00007fdcf20bd493 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000 R13: 00007fffbb8d7bdf R14: 00007fdcf13e3300 R15: 0000000000022000

The buggy address belongs to the variable: rmnet_policy+0x30/0xe0

The buggy address belongs to the physical page: page:0000000065bdeb3c refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x155243 flags: 0x200000000001000(reserved|node=0|zone=2) raw: 0200000000001000 ffffea00055490c8 ffffea00055490c8 0000000000000000 raw: 0000000000000000 0000000000000000 00000001ffffffff 0000000000000000 page dumped because: kasan: bad access detected

Memory state around the buggy address: ffffffff92c43780: f9 f9 f9 f9 00 00 00 02 f9 f9 f9 f9 00 00 00 07 ffffffff92c43800: f9 f9 f9 f9 00 00 00 05 f9 f9 f9 f9 06 f9 f9 f9

ffffffff92c43880: f9 f9 f9 f9 00 00 00 00 00 00 f9 f9 f9 f9 f9 f9 ^ ffffffff92c43900: 00 00 00 00 00 00 00 00 07 f9 f9 f9 f9 f9 f9 f9 ffffffff92c43980: 00 00 00 07 f9 f9 f9 f9 00 00 00 05 f9 f9 f9 f9

According to the comment of nla_parse_nested_deprecated, the maxtype should be len(destination array) - 1. Hence use IFLA_RMNET_MAX here.

Weakness

The product reads data past the end, or before the beginning, of the intended buffer.

Affected Software

Potential Mitigations

• Assume all input is malicious. Use an “accept known good” input validation strategy, i.e., use a list of acceptable inputs that strictly conform to specifications. Reject any input that does not strictly conform to specifications, or transform it into something that does.
• When performing input validation, consider all potentially relevant properties, including length, type of input, the full range of acceptable values, missing or extra inputs, syntax, consistency across related fields, and conformance to business rules. As an example of business rule logic, “boat” may be syntactically valid because it only contains alphanumeric characters, but it is not valid if the input is only expected to contain colors such as “red” or “blue.”
• Do not rely exclusively on looking for malicious or malformed inputs. This is likely to miss at least one undesirable input, especially if the code’s environment changes. This can give attackers enough room to bypass the intended validation. However, denylists can be useful for detecting potential attacks or determining which inputs are so malformed that they should be rejected outright.
• To reduce the likelihood of introducing an out-of-bounds read, ensure that you validate and ensure correct calculations for any length argument, buffer size calculation, or offset. Be especially careful of relying on a sentinel (i.e. special character such as NUL) in untrusted inputs.

Related Attack Patterns

• https://cwe.mitre.org/data/definitions/540.html

References

• https://git.kernel.org/stable/c/02467ab8b404d80429107588e0f3425cf5fcd2e5
• https://git.kernel.org/stable/c/093dab655808207f7a9f54cf156240aeafc70590
• https://git.kernel.org/stable/c/17d06a5c44d8fd2e8e61bac295b09153496f87e1
• https://git.kernel.org/stable/c/2295c22348faf795e1ccdf618f6eb7afdb2f7447
• https://git.kernel.org/stable/c/3b5254862258b595662a0ccca6e9eeb88d6e7468
• https://git.kernel.org/stable/c/b33fb5b801c6db408b774a68e7c8722796b59ecc
• https://git.kernel.org/stable/c/c4734535034672f59f2652e1e0058c490da62a5c
• https://git.kernel.org/stable/c/ee1dc3bf86f2df777038506b139371a9add02534