CVE-2022-49658

/// Technical description

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=(0x7

/// Remediation

Check the references section for vendor advisories, patches, and mitigation guidance. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.

/// References