CVE-2024-43837
- Source
- https://nvd.nist.gov/vuln/detail/CVE-2024-43837
- Import Source
- https://storage.googleapis.com/osv-test-cve-osv-conversion/osv-output/CVE-2024-43837.json
- JSON Data
- https://api.test.osv.dev/v1/vulns/CVE-2024-43837
- Downstream
- Related
- Published
- 2024-08-17T09:21:53Z
- Modified
- 2025-10-17T10:34:20.256238Z
- Summary
- bpf: Fix null pointer dereference in resolve_prog_type() for BPF_PROG_TYPE_EXT
- Details
-
In the Linux kernel, the following vulnerability has been resolved:
bpf: Fix null pointer dereference in resolveprogtype() for BPFPROGTYPE_EXT
When loading a EXT program without specifying
attr->attach_prog_fd, theprog->aux->dst_progwill be null. At this time, calling resolveprogtype() 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: mayaccessdire 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 : mayaccessdirectpktdata+0x24/0xa0 [ 8.113746] lr : addsubprogandkfunc+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] mayaccessdirectpktdata+0x24/0xa0 [ 8.114202] bpfcheck+0x3bc/0x28c0 [ 8.114214] bpfprogload+0x658/0xa58 [ 8.114227] _sysbpf+0xc50/0x2250 [ 8.114240] _arm64sysbpf+0x28/0x40 [ 8.114254] invokesyscall.constprop.0+0x54/0xf0 [ 8.114273] doel0svc+0x4c/0xd8 [ 8.114289] el0svc+0x3c/0x140 [ 8.114305] el0t64synchandler+0x134/0x150 [ 8.114331] el0t64sync+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_fdnon-empty when bpfprogload(). But this will lead tolibbpf_probe_bpf_prog_typeAPI 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 resolveprogtype().
The issue was introduced by commit 4a9c7bbe2ed4 ("bpf: Resolve to prog->aux->dstprog->type only for BPFPROGTYPEEXT") which wanted to correct type resolution for BPFPROGTYPETRACING programs. Before that, the type resolution of BPFPROGTYPEEXT prog actually follows the logic below:
prog->aux->dstprog ? prog->aux->dstprog->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->typefor BPFPROGTYPEEXT ifdst_progis not present in resolveprog_type(). - References
-
- https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git
- https://git.kernel.org/stable/c/9d40fd516aeae6779e3c84c6b96700ca76285847
- https://git.kernel.org/stable/c/b29a880bb145e1f1c1df5ab88ed26b1495ff9f09
- https://git.kernel.org/stable/c/f7866c35873377313ff94398f17d425b28b71de1
- https://git.kernel.org/stable/c/fcac5feb06f31ee4c88bca9bf98d8bc3ca7d2615
Affected packages
Git / git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git
Affected ranges
- Type
- GIT
- Repo
- https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git
- Events
-
Introduced4a9c7bbe2ed4d2b240674b1fb606c41d3940c412Fixedfcac5feb06f31ee4c88bca9bf98d8bc3ca7d2615
- Type
- GIT
- Repo
- https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git
- Events
-
Introduced4a9c7bbe2ed4d2b240674b1fb606c41d3940c412Fixed9d40fd516aeae6779e3c84c6b96700ca76285847
- Type
- GIT
- Repo
- https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git
- Events
-
Introduced4a9c7bbe2ed4d2b240674b1fb606c41d3940c412Fixedb29a880bb145e1f1c1df5ab88ed26b1495ff9f09
- Type
- GIT
- Repo
- https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git
- Events
-
Introduced4a9c7bbe2ed4d2b240674b1fb606c41d3940c412Fixedf7866c35873377313ff94398f17d425b28b71de1
Affected versions
v5.*
v6.*
Database specific
vanir_signatures
[
{
"signature_type": "Line",
"deprecated": false,
"source": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git@b29a880bb145e1f1c1df5ab88ed26b1495ff9f09",
"signature_version": "v1",
"target": {
"file": "include/linux/bpf_verifier.h"
},
"digest": {
"threshold": 0.9,
"line_hashes": [
"26274091560468632788080403896241758732",
"299487938658815896081440408727113478176",
"290777485744559376279234023506199155772",
"257731589538046347317610767496952496224"
]
},
"id": "CVE-2024-43837-0ed5271d"
},
{
"signature_type": "Function",
"deprecated": false,
"source": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git@9d40fd516aeae6779e3c84c6b96700ca76285847",
"signature_version": "v1",
"target": {
"function": "resolve_prog_type",
"file": "include/linux/bpf_verifier.h"
},
"digest": {
"function_hash": "318338540772419881703440585586201538194",
"length": 151.0
},
"id": "CVE-2024-43837-23182bde"
},
{
"signature_type": "Function",
"deprecated": false,
"source": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git@f7866c35873377313ff94398f17d425b28b71de1",
"signature_version": "v1",
"target": {
"function": "resolve_prog_type",
"file": "include/linux/bpf_verifier.h"
},
"digest": {
"function_hash": "318338540772419881703440585586201538194",
"length": 151.0
},
"id": "CVE-2024-43837-4051dc71"
},
{
"signature_type": "Function",
"deprecated": false,
"source": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git@fcac5feb06f31ee4c88bca9bf98d8bc3ca7d2615",
"signature_version": "v1",
"target": {
"function": "resolve_prog_type",
"file": "include/linux/bpf_verifier.h"
},
"digest": {
"function_hash": "318338540772419881703440585586201538194",
"length": 151.0
},
"id": "CVE-2024-43837-574eac0c"
},
{
"signature_type": "Line",
"deprecated": false,
"source": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git@f7866c35873377313ff94398f17d425b28b71de1",
"signature_version": "v1",
"target": {
"file": "include/linux/bpf_verifier.h"
},
"digest": {
"threshold": 0.9,
"line_hashes": [
"26274091560468632788080403896241758732",
"299487938658815896081440408727113478176",
"290777485744559376279234023506199155772",
"257731589538046347317610767496952496224"
]
},
"id": "CVE-2024-43837-63e57de0"
},
{
"signature_type": "Line",
"deprecated": false,
"source": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git@9d40fd516aeae6779e3c84c6b96700ca76285847",
"signature_version": "v1",
"target": {
"file": "include/linux/bpf_verifier.h"
},
"digest": {
"threshold": 0.9,
"line_hashes": [
"26274091560468632788080403896241758732",
"299487938658815896081440408727113478176",
"290777485744559376279234023506199155772",
"257731589538046347317610767496952496224"
]
},
"id": "CVE-2024-43837-69ea0d49"
},
{
"signature_type": "Function",
"deprecated": false,
"source": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git@b29a880bb145e1f1c1df5ab88ed26b1495ff9f09",
"signature_version": "v1",
"target": {
"function": "resolve_prog_type",
"file": "include/linux/bpf_verifier.h"
},
"digest": {
"function_hash": "318338540772419881703440585586201538194",
"length": 151.0
},
"id": "CVE-2024-43837-79ccbf2b"
},
{
"signature_type": "Line",
"deprecated": false,
"source": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git@fcac5feb06f31ee4c88bca9bf98d8bc3ca7d2615",
"signature_version": "v1",
"target": {
"file": "include/linux/bpf_verifier.h"
},
"digest": {
"threshold": 0.9,
"line_hashes": [
"26274091560468632788080403896241758732",
"299487938658815896081440408727113478176",
"290777485744559376279234023506199155772",
"257731589538046347317610767496952496224"
]
},
"id": "CVE-2024-43837-990c26a4"
}
]