bpf: sync_linked_regs() must preserve subreg_def
- Published
- Last modified
- Where the record stands: published, rejected by its publisher, or superseded by another id.What do these mean? →
- published
- Whether CISA lists it in its Known Exploited Vulnerabilities catalog: proof that attackers are using it.What do these mean? →
- Not listed in CISA KEV
- Fix
- Fixed in 5.10.232, 5.15.175, 6.1.121, 6.6.67, 6.11.6
- Whether working attack code is public (Exploit-DB, Metasploit, Nuclei or GitHub). Public code makes attacks easier.What do these mean? →
- None on Exploit-DB, Metasploit or GitHub
- Exploitation: none
- Automatable: no
- Technical impact: total
Summary
In the Linux kernel, the following vulnerability has been resolved: bpf: sync_linked_regs() must preserve subreg_def Range propagation must not affect subreg_def marks, otherwise the following example is rewritten by verifier incorrectly when BPF_F_TEST_RND_HI32 flag is set: 0: call bpf_ktime_get_ns call bpf_ktime_get_ns 1: r0 &= 0x7fffffff after verifier r0 &= 0x7fffffff 2: w1 = w0 rewrites w1 = w0 3: if w0 < 10 goto +0 --------------> r11 = 0x2f5674a6 (r) 4: r1 >>= 32 r11 <<= 32 (r) 5: r0 = r1 r1 |= r11 (r) 6: exit; if w0 < 0xa goto pc+0 r1 >>= 32 r0 = r1 exit (or zero extension of w1 at (2) is missing for architectures that require zero extension for upper register half). The following happens w/o this patch: • r0 is marked as not a subreg at (0); • w1 is marked as subreg at (2); • w1 subreg_def is overridden at (3) by copy_register_state(); • w1 is read at (5) but mark_insn_zext() does not mark (2) for zero extension, because w1 subreg_def is not set; • because of BPF_F_TEST_RND_HI32 flag verifier inserts random value for hi32 bits of (2) (marked (r)); • this random value is read at (5).
Timeline
- CVE published
- CISA SSVC assessment
Exploitation: none · Automatable: no · Technical impact: total
- Record last updated
Affected versions
- Linux Linux
From 75748837b7e56919679e02163f45d5818c644d03 · fixed in dadf82c1b2608727bcc306843b540cd7414055a7; From 75748837b7e56919679e02163f45d5818c644d03 · fixed in b57ac2d92c1f565743f6890a5b9cf317ed856b09; From 75748837b7e56919679e02163f45d5818c644d03 · fixed in 60fd3538d2a8fd44c41d25088c0ece3e1fd30659; From 75748837b7e56919679e02163f45d5818c644d03 · fixed in bfe9446ea1d95f6cb7848da19dfd58d2eec6fd84; From 75748837b7e56919679e02163f45d5818c644d03 · fixed in e2ef0f317a52e678fe8fa84b94d6a15b466d6ff0; From 75748837b7e56919679e02163f45d5818c644d03 · fixed in e9bd9c498cb0f5843996dbe5cbce7a1836a83c70
- Linux Linux
5.10
- KernelLinux
From 5.10.0 · fixed in 5.10.232; From 5.11.0 · fixed in 5.15.175; From 5.16.0 · fixed in 6.1.121; From 6.2.0 · fixed in 6.6.67; From 6.7.0 · fixed in 6.11.6