ghsa-hfgw-x7g5-fgj8
Vulnerability from github
In the Linux kernel, the following vulnerability has been resolved:
bpf: Fix insufficient bounds propagation from adjust_scalar_min_max_vals
Kuee reported a corner case where the tnum becomes constant after the call to __reg_bound_offset(), but the register's bounds are not, that is, its min bounds are still not equal to the register's max bounds.
This in turn allows to leak pointers through turning a pointer register as is into an unknown scalar via adjust_ptr_min_max_vals().
Before:
func#0 @0 0: R1=ctx(off=0,imm=0,umax=0,var_off=(0x0; 0x0)) R10=fp(off=0,imm=0,umax=0,var_off=(0x0; 0x0)) 0: (b7) r0 = 1 ; R0_w=scalar(imm=1,umin=1,umax=1,var_off=(0x1; 0x0)) 1: (b7) r3 = 0 ; R3_w=scalar(imm=0,umax=0,var_off=(0x0; 0x0)) 2: (87) r3 = -r3 ; R3_w=scalar() 3: (87) r3 = -r3 ; R3_w=scalar() 4: (47) r3 |= 32767 ; R3_w=scalar(smin=-9223372036854743041,umin=32767,var_off=(0x7fff; 0xffffffffffff8000),s32_min=-2147450881) 5: (75) if r3 s>= 0x0 goto pc+1 ; R3_w=scalar(umin=9223372036854808575,var_off=(0x8000000000007fff; 0x7fffffffffff8000),s32_min=-2147450881,u32_min=32767) 6: (95) exit
from 5 to 7: R0=scalar(imm=1,umin=1,umax=1,var_off=(0x1; 0x0)) R1=ctx(off=0,imm=0,umax=0,var_off=(0x0; 0x0)) R3=scalar(umin=32767,umax=9223372036854775807,var_off=(0x7fff; 0x7fffffffffff8000),s32_min=-2147450881) R10=fp(off=0,imm=0,umax=0,var_off=(0x0; 0x0)) 7: (d5) if r3 s<= 0x8000 goto pc+1 ; R3=scalar(umin=32769,umax=9223372036854775807,var_off=(0x7fff; 0x7fffffffffff8000),s32_min=-2147450881,u32_min=32767) 8: (95) exit
from 7 to 9: R0=scalar(imm=1,umin=1,umax=1,var_off=(0x1; 0x0)) R1=ctx(off=0,imm=0,umax=0,var_off=(0x0; 0x0)) R3=scalar(umin=32767,umax=32768,var_off=(0x7fff; 0x8000)) R10=fp(off=0,imm=0,umax=0,var_off=(0x0; 0x0)) 9: (07) r3 += -32767 ; R3_w=scalar(imm=0,umax=1,var_off=(0x0; 0x0)) <--- [*] 10: (95) exit
What can be seen here is that R3=scalar(umin=32767,umax=32768,var_off=(0x7fff; 0x8000)) after the operation R3 += -32767 results in a 'malformed' constant, that is, R3_w=scalar(imm=0,umax=1,var_off=(0x0; 0x0)). Intersecting with var_off has not been done at that point via __update_reg_bounds(), which would have improved the umax to be equal to umin.
Refactor the tnum <> min/max bounds information flow into a reg_bounds_sync() helper and use it consistently everywhere. After the fix, bounds have been corrected to R3_w=scalar(imm=0,umax=0,var_off=(0x0; 0x0)) and thus the register is regarded as a 'proper' constant scalar of 0.
After:
func#0 @0 0: R1=ctx(off=0,imm=0,umax=0,var_off=(0x0; 0x0)) R10=fp(off=0,imm=0,umax=0,var_off=(0x0; 0x0)) 0: (b7) r0 = 1 ; R0_w=scalar(imm=1,umin=1,umax=1,var_off=(0x1; 0x0)) 1: (b7) r3 = 0 ; R3_w=scalar(imm=0,umax=0,var_off=(0x0; 0x0)) 2: (87) r3 = -r3 ; R3_w=scalar() 3: (87) r3 = -r3 ; R3_w=scalar() 4: (47) r3 |= 32767 ; R3_w=scalar(smin=-9223372036854743041,umin=32767,var_off=(0x7fff; 0xffffffffffff8000),s32_min=-2147450881) 5: (75) if r3 s>= 0x0 goto pc+1 ; R3_w=scalar(umin=9223372036854808575,var_off=(0x8000000000007fff; 0x7fffffffffff8000),s32_min=-2147450881,u32_min=32767) 6: (95) exit
from 5 to 7: R0=scalar(imm=1,umin=1,umax=1,var_off=(0x1; 0x0)) R1=ctx(off=0,imm=0,umax=0,var_off=(0x0; 0x0)) R3=scalar(umin=32767,umax=9223372036854775807,var_off=(0x7fff; 0x7fffffffffff8000),s32_min=-2147450881) R10=fp(off=0,imm=0,umax=0,var_off=(0x0; 0x0)) 7: (d5) if r3 s<= 0x8000 goto pc+1 ; R3=scalar(umin=32769,umax=9223372036854775807,var_off=(0x7fff; 0x7fffffffffff8000),s32_min=-2147450881,u32_min=32767) 8: (95) exit
from 7 to 9: R0=scalar(imm=1,umin=1,umax=1,var_off=(0x1; 0x0)) R1=ctx(off=0,imm=0,umax=0,var_off=(0x0; 0x0)) R3=scalar(umin=32767,umax=32768,var_off=(0x7fff; 0x8000)) R10=fp(off=0 ---truncated---
{
"affected": [],
"aliases": [
"CVE-2022-49658"
],
"database_specific": {
"cwe_ids": [],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2025-02-26T07:01:40Z",
"severity": "MODERATE"
},
"details": "In the Linux kernel, the following vulnerability has been resolved:\n\nbpf: Fix insufficient bounds propagation from adjust_scalar_min_max_vals\n\nKuee reported a corner case where the tnum becomes constant after the call\nto __reg_bound_offset(), but the register\u0027s bounds are not, that is, its\nmin bounds are still not equal to the register\u0027s max bounds.\n\nThis in turn allows to leak pointers through turning a pointer register as\nis into an unknown scalar via adjust_ptr_min_max_vals().\n\nBefore:\n\n func#0 @0\n 0: R1=ctx(off=0,imm=0,umax=0,var_off=(0x0; 0x0)) R10=fp(off=0,imm=0,umax=0,var_off=(0x0; 0x0))\n 0: (b7) r0 = 1 ; R0_w=scalar(imm=1,umin=1,umax=1,var_off=(0x1; 0x0))\n 1: (b7) r3 = 0 ; R3_w=scalar(imm=0,umax=0,var_off=(0x0; 0x0))\n 2: (87) r3 = -r3 ; R3_w=scalar()\n 3: (87) r3 = -r3 ; R3_w=scalar()\n 4: (47) r3 |= 32767 ; R3_w=scalar(smin=-9223372036854743041,umin=32767,var_off=(0x7fff; 0xffffffffffff8000),s32_min=-2147450881)\n 5: (75) if r3 s\u003e= 0x0 goto pc+1 ; R3_w=scalar(umin=9223372036854808575,var_off=(0x8000000000007fff; 0x7fffffffffff8000),s32_min=-2147450881,u32_min=32767)\n 6: (95) exit\n\n from 5 to 7: R0=scalar(imm=1,umin=1,umax=1,var_off=(0x1; 0x0)) R1=ctx(off=0,imm=0,umax=0,var_off=(0x0; 0x0)) R3=scalar(umin=32767,umax=9223372036854775807,var_off=(0x7fff; 0x7fffffffffff8000),s32_min=-2147450881) R10=fp(off=0,imm=0,umax=0,var_off=(0x0; 0x0))\n 7: (d5) if r3 s\u003c= 0x8000 goto pc+1 ; R3=scalar(umin=32769,umax=9223372036854775807,var_off=(0x7fff; 0x7fffffffffff8000),s32_min=-2147450881,u32_min=32767)\n 8: (95) exit\n\n from 7 to 9: R0=scalar(imm=1,umin=1,umax=1,var_off=(0x1; 0x0)) R1=ctx(off=0,imm=0,umax=0,var_off=(0x0; 0x0)) R3=scalar(umin=32767,umax=32768,var_off=(0x7fff; 0x8000)) R10=fp(off=0,imm=0,umax=0,var_off=(0x0; 0x0))\n 9: (07) r3 += -32767 ; R3_w=scalar(imm=0,umax=1,var_off=(0x0; 0x0)) \u003c--- [*]\n 10: (95) exit\n\nWhat can be seen here is that R3=scalar(umin=32767,umax=32768,var_off=(0x7fff;\n0x8000)) after the operation R3 += -32767 results in a \u0027malformed\u0027 constant, that\nis, R3_w=scalar(imm=0,umax=1,var_off=(0x0; 0x0)). Intersecting with var_off has\nnot been done at that point via __update_reg_bounds(), which would have improved\nthe umax to be equal to umin.\n\nRefactor the tnum \u003c\u003e min/max bounds information flow into a reg_bounds_sync()\nhelper and use it consistently everywhere. After the fix, bounds have been\ncorrected to R3_w=scalar(imm=0,umax=0,var_off=(0x0; 0x0)) and thus the register\nis regarded as a \u0027proper\u0027 constant scalar of 0.\n\nAfter:\n\n func#0 @0\n 0: R1=ctx(off=0,imm=0,umax=0,var_off=(0x0; 0x0)) R10=fp(off=0,imm=0,umax=0,var_off=(0x0; 0x0))\n 0: (b7) r0 = 1 ; R0_w=scalar(imm=1,umin=1,umax=1,var_off=(0x1; 0x0))\n 1: (b7) r3 = 0 ; R3_w=scalar(imm=0,umax=0,var_off=(0x0; 0x0))\n 2: (87) r3 = -r3 ; R3_w=scalar()\n 3: (87) r3 = -r3 ; R3_w=scalar()\n 4: (47) r3 |= 32767 ; R3_w=scalar(smin=-9223372036854743041,umin=32767,var_off=(0x7fff; 0xffffffffffff8000),s32_min=-2147450881)\n 5: (75) if r3 s\u003e= 0x0 goto pc+1 ; R3_w=scalar(umin=9223372036854808575,var_off=(0x8000000000007fff; 0x7fffffffffff8000),s32_min=-2147450881,u32_min=32767)\n 6: (95) exit\n\n from 5 to 7: R0=scalar(imm=1,umin=1,umax=1,var_off=(0x1; 0x0)) R1=ctx(off=0,imm=0,umax=0,var_off=(0x0; 0x0)) R3=scalar(umin=32767,umax=9223372036854775807,var_off=(0x7fff; 0x7fffffffffff8000),s32_min=-2147450881) R10=fp(off=0,imm=0,umax=0,var_off=(0x0; 0x0))\n 7: (d5) if r3 s\u003c= 0x8000 goto pc+1 ; R3=scalar(umin=32769,umax=9223372036854775807,var_off=(0x7fff; 0x7fffffffffff8000),s32_min=-2147450881,u32_min=32767)\n 8: (95) exit\n\n from 7 to 9: R0=scalar(imm=1,umin=1,umax=1,var_off=(0x1; 0x0)) R1=ctx(off=0,imm=0,umax=0,var_off=(0x0; 0x0)) R3=scalar(umin=32767,umax=32768,var_off=(0x7fff; 0x8000)) R10=fp(off=0\n---truncated---",
"id": "GHSA-hfgw-x7g5-fgj8",
"modified": "2025-10-23T12:31:16Z",
"published": "2025-10-23T12:31:16Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2022-49658"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/3844d153a41adea718202c10ae91dc96b37453b5"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/a7de8d436db92bab8b1f44624297c2554a6ac36b"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/b2a28bb36664c94375926cbbb91976242847699d"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/e917be1f83ea14a68b3cf64d3da9968eaf991dae"
}
],
"schema_version": "1.4.0",
"severity": [
{
"score": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H",
"type": "CVSS_V3"
}
]
}
Sightings
| Author | Source | Type | Date |
|---|
Nomenclature
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