CVE-2024-43837
Linux BPF Null Pointer Dereference Vulnerability
Description
In the Linux kernel, the following vulnerability has been resolved: bpf: Fix null pointer dereference in resolve_prog_type() for BPF_PROG_TYPE_EXT When loading a EXT program without specifying `attr->attach_prog_fd`, the `prog->aux->dst_prog` will be null. At this time, calling resolve_prog_type() anywhere will result in a null pointer dereference. Example stack trace: [ 8.107863] Unable to handle kernel NULL pointer dereference at virtual address 0000000000000004 [ 8.108262] Mem abort info: [ 8.108384] ESR = 0x0000000096000004 [ 8.108547] EC = 0x25: DABT (current EL), IL = 32 bits [ 8.108722] SET = 0, FnV = 0 [ 8.108827] EA = 0, S1PTW = 0 [ 8.108939] FSC = 0x04: level 0 translation fault [ 8.109102] Data abort info: [ 8.109203] ISV = 0, ISS = 0x00000004, ISS2 = 0x00000000 [ 8.109399] CM = 0, WnR = 0, TnD = 0, TagAccess = 0 [ 8.109614] GCS = 0, Overlay = 0, DirtyBit = 0, Xs = 0 [ 8.109836] user pgtable: 4k pages, 48-bit VAs, pgdp=0000000101354000 [ 8.110011] [0000000000000004] pgd=0000000000000000, p4d=0000000000000000 [ 8.112624] Internal error: Oops: 0000000096000004 [#1] PREEMPT SMP [ 8.112783] Modules linked in: [ 8.113120] CPU: 0 PID: 99 Comm: may_access_dire Not tainted 6.10.0-rc3-next-20240613-dirty #1 [ 8.113230] Hardware name: linux,dummy-virt (DT) [ 8.113390] pstate: 60000005 (nZCv daif -PAN -UAO -TCO -DIT -SSBS BTYPE=--) [ 8.113429] pc : may_access_direct_pkt_data+0x24/0xa0 [ 8.113746] lr : add_subprog_and_kfunc+0x634/0x8e8 [ 8.113798] sp : ffff80008283b9f0 [ 8.113813] x29: ffff80008283b9f0 x28: ffff800082795048 x27: 0000000000000001 [ 8.113881] x26: ffff0000c0bb2600 x25: 0000000000000000 x24: 0000000000000000 [ 8.113897] x23: ffff0000c1134000 x22: 000000000001864f x21: ffff0000c1138000 [ 8.113912] x20: 0000000000000001 x19: ffff0000c12b8000 x18: ffffffffffffffff [ 8.113929] x17: 0000000000000000 x16: 0000000000000000 x15: 0720072007200720 [ 8.113944] x14: 0720072007200720 x13: 0720072007200720 x12: 0720072007200720 [ 8.113958] x11: 0720072007200720 x10: 0000000000f9fca4 x9 : ffff80008021f4e4 [ 8.113991] x8 : 0101010101010101 x7 : 746f72705f6d656d x6 : 000000001e0e0f5f [ 8.114006] x5 : 000000000001864f x4 : ffff0000c12b8000 x3 : 000000000000001c [ 8.114020] x2 : 0000000000000002 x1 : 0000000000000000 x0 : 0000000000000000 [ 8.114126] Call trace: [ 8.114159] may_access_direct_pkt_data+0x24/0xa0 [ 8.114202] bpf_check+0x3bc/0x28c0 [ 8.114214] bpf_prog_load+0x658/0xa58 [ 8.114227] __sys_bpf+0xc50/0x2250 [ 8.114240] __arm64_sys_bpf+0x28/0x40 [ 8.114254] invoke_syscall.constprop.0+0x54/0xf0 [ 8.114273] do_el0_svc+0x4c/0xd8 [ 8.114289] el0_svc+0x3c/0x140 [ 8.114305] el0t_64_sync_handler+0x134/0x150 [ 8.114331] el0t_64_sync+0x168/0x170 [ 8.114477] Code: 7100707f 54000081 f9401c00 f9403800 (b9400403) [ 8.118672] ---[ end trace 0000000000000000 ]--- One way to fix it is by forcing `attach_prog_fd` non-empty when bpf_prog_load(). But this will lead to `libbpf_probe_bpf_prog_type` API broken which use verifier log to probe prog type and will log nothing if we reject invalid EXT prog before bpf_check(). Another way is by adding null check in resolve_prog_type(). The issue was introduced by commit 4a9c7bbe2ed4 ("bpf: Resolve to prog->aux->dst_prog->type only for BPF_PROG_TYPE_EXT") which wanted to correct type resolution for BPF_PROG_TYPE_TRACING programs. Before that, the type resolution of BPF_PROG_TYPE_EXT prog actually follows the logic below: prog->aux->dst_prog ? prog->aux->dst_prog->type : prog->type; It implies that when EXT program is not yet attached to `dst_prog`, the prog type should be EXT itself. This code worked fine in the past. So just keep using it. Fix this by returning `prog->type` for BPF_PROG_TYPE_EXT if `dst_prog` is not present in resolve_prog_type().
INFO
Published Date :
Aug. 17, 2024, 10:15 a.m.
Last Modified :
Aug. 22, 2024, 3:44 p.m.
Source :
416baaa9-dc9f-4396-8d5f-8c081fb06d67
Remotely Exploitable :
No
Impact Score :
3.6
Exploitability Score :
1.8
References to Advisories, Solutions, and Tools
Here, you will find a curated list of external links that provide in-depth
information, practical solutions, and valuable tools related to
CVE-2024-43837.
We scan GitHub repositories to detect new proof-of-concept exploits. Following list is a collection of public exploits and proof-of-concepts, which have been published on GitHub (sorted by the most recently updated).
Results are limited to the first 15 repositories due to potential performance issues.
The following list is the news that have been mention
CVE-2024-43837 vulnerability anywhere in the article.
The following table lists the changes that have been made to the
CVE-2024-43837 vulnerability over time.
Vulnerability history details can be useful for understanding the evolution of a vulnerability, and for identifying the most recent changes that may impact the vulnerability's severity, exploitability, or other characteristics.
-
Initial Analysis by [email protected]
Aug. 22, 2024
Action Type Old Value New Value Added CVSS V3.1 NIST AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H Changed Reference Type https://git.kernel.org/stable/c/9d40fd516aeae6779e3c84c6b96700ca76285847 No Types Assigned https://git.kernel.org/stable/c/9d40fd516aeae6779e3c84c6b96700ca76285847 Patch Changed Reference Type https://git.kernel.org/stable/c/b29a880bb145e1f1c1df5ab88ed26b1495ff9f09 No Types Assigned https://git.kernel.org/stable/c/b29a880bb145e1f1c1df5ab88ed26b1495ff9f09 Patch Changed Reference Type https://git.kernel.org/stable/c/f7866c35873377313ff94398f17d425b28b71de1 No Types Assigned https://git.kernel.org/stable/c/f7866c35873377313ff94398f17d425b28b71de1 Patch Changed Reference Type https://git.kernel.org/stable/c/fcac5feb06f31ee4c88bca9bf98d8bc3ca7d2615 No Types Assigned https://git.kernel.org/stable/c/fcac5feb06f31ee4c88bca9bf98d8bc3ca7d2615 Patch Added CWE NIST CWE-476 Added CPE Configuration OR *cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:* versions from (including) 5.18 up to (excluding) 6.1.103 *cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:* versions from (including) 6.2 up to (excluding) 6.6.44 *cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:* versions from (including) 6.7 up to (excluding) 6.10.3 -
CVE Received by 416baaa9-dc9f-4396-8d5f-8c081fb06d67
Aug. 17, 2024
Action Type Old Value New Value Added Description In the Linux kernel, the following vulnerability has been resolved: bpf: Fix null pointer dereference in resolve_prog_type() for BPF_PROG_TYPE_EXT When loading a EXT program without specifying `attr->attach_prog_fd`, the `prog->aux->dst_prog` will be null. At this time, calling resolve_prog_type() anywhere will result in a null pointer dereference. Example stack trace: [ 8.107863] Unable to handle kernel NULL pointer dereference at virtual address 0000000000000004 [ 8.108262] Mem abort info: [ 8.108384] ESR = 0x0000000096000004 [ 8.108547] EC = 0x25: DABT (current EL), IL = 32 bits [ 8.108722] SET = 0, FnV = 0 [ 8.108827] EA = 0, S1PTW = 0 [ 8.108939] FSC = 0x04: level 0 translation fault [ 8.109102] Data abort info: [ 8.109203] ISV = 0, ISS = 0x00000004, ISS2 = 0x00000000 [ 8.109399] CM = 0, WnR = 0, TnD = 0, TagAccess = 0 [ 8.109614] GCS = 0, Overlay = 0, DirtyBit = 0, Xs = 0 [ 8.109836] user pgtable: 4k pages, 48-bit VAs, pgdp=0000000101354000 [ 8.110011] [0000000000000004] pgd=0000000000000000, p4d=0000000000000000 [ 8.112624] Internal error: Oops: 0000000096000004 [#1] PREEMPT SMP [ 8.112783] Modules linked in: [ 8.113120] CPU: 0 PID: 99 Comm: may_access_dire Not tainted 6.10.0-rc3-next-20240613-dirty #1 [ 8.113230] Hardware name: linux,dummy-virt (DT) [ 8.113390] pstate: 60000005 (nZCv daif -PAN -UAO -TCO -DIT -SSBS BTYPE=--) [ 8.113429] pc : may_access_direct_pkt_data+0x24/0xa0 [ 8.113746] lr : add_subprog_and_kfunc+0x634/0x8e8 [ 8.113798] sp : ffff80008283b9f0 [ 8.113813] x29: ffff80008283b9f0 x28: ffff800082795048 x27: 0000000000000001 [ 8.113881] x26: ffff0000c0bb2600 x25: 0000000000000000 x24: 0000000000000000 [ 8.113897] x23: ffff0000c1134000 x22: 000000000001864f x21: ffff0000c1138000 [ 8.113912] x20: 0000000000000001 x19: ffff0000c12b8000 x18: ffffffffffffffff [ 8.113929] x17: 0000000000000000 x16: 0000000000000000 x15: 0720072007200720 [ 8.113944] x14: 0720072007200720 x13: 0720072007200720 x12: 0720072007200720 [ 8.113958] x11: 0720072007200720 x10: 0000000000f9fca4 x9 : ffff80008021f4e4 [ 8.113991] x8 : 0101010101010101 x7 : 746f72705f6d656d x6 : 000000001e0e0f5f [ 8.114006] x5 : 000000000001864f x4 : ffff0000c12b8000 x3 : 000000000000001c [ 8.114020] x2 : 0000000000000002 x1 : 0000000000000000 x0 : 0000000000000000 [ 8.114126] Call trace: [ 8.114159] may_access_direct_pkt_data+0x24/0xa0 [ 8.114202] bpf_check+0x3bc/0x28c0 [ 8.114214] bpf_prog_load+0x658/0xa58 [ 8.114227] __sys_bpf+0xc50/0x2250 [ 8.114240] __arm64_sys_bpf+0x28/0x40 [ 8.114254] invoke_syscall.constprop.0+0x54/0xf0 [ 8.114273] do_el0_svc+0x4c/0xd8 [ 8.114289] el0_svc+0x3c/0x140 [ 8.114305] el0t_64_sync_handler+0x134/0x150 [ 8.114331] el0t_64_sync+0x168/0x170 [ 8.114477] Code: 7100707f 54000081 f9401c00 f9403800 (b9400403) [ 8.118672] ---[ end trace 0000000000000000 ]--- One way to fix it is by forcing `attach_prog_fd` non-empty when bpf_prog_load(). But this will lead to `libbpf_probe_bpf_prog_type` API broken which use verifier log to probe prog type and will log nothing if we reject invalid EXT prog before bpf_check(). Another way is by adding null check in resolve_prog_type(). The issue was introduced by commit 4a9c7bbe2ed4 ("bpf: Resolve to prog->aux->dst_prog->type only for BPF_PROG_TYPE_EXT") which wanted to correct type resolution for BPF_PROG_TYPE_TRACING programs. Before that, the type resolution of BPF_PROG_TYPE_EXT prog actually follows the logic below: prog->aux->dst_prog ? prog->aux->dst_prog->type : prog->type; It implies that when EXT program is not yet attached to `dst_prog`, the prog type should be EXT itself. This code worked fine in the past. So just keep using it. Fix this by returning `prog->type` for BPF_PROG_TYPE_EXT if `dst_prog` is not present in resolve_prog_type(). Added Reference kernel.org https://git.kernel.org/stable/c/fcac5feb06f31ee4c88bca9bf98d8bc3ca7d2615 [No types assigned] Added Reference kernel.org https://git.kernel.org/stable/c/9d40fd516aeae6779e3c84c6b96700ca76285847 [No types assigned] Added Reference kernel.org https://git.kernel.org/stable/c/b29a880bb145e1f1c1df5ab88ed26b1495ff9f09 [No types assigned] Added Reference kernel.org https://git.kernel.org/stable/c/f7866c35873377313ff94398f17d425b28b71de1 [No types assigned]
CWE - Common Weakness Enumeration
While CVE identifies
specific instances of vulnerabilities, CWE categorizes the common flaws or
weaknesses that can lead to vulnerabilities. CVE-2024-43837 is
associated with the following CWEs:
Common Attack Pattern Enumeration and Classification (CAPEC)
Common Attack Pattern Enumeration and Classification
(CAPEC)
stores attack patterns, which are descriptions of the common attributes and
approaches employed by adversaries to exploit the CVE-2024-43837
weaknesses.