bpf: Fix abuse of kprobe_write_ctx via freplace
3Vexday Risk Score
No sign of exploitation. No public exploitation artifact known so far.
ssvc Trackepss 0.1%
exploitation probability
0.1%top 98% of all CVEs
observed exploitation
nono source reports it
In the Linux kernel, the following vulnerability has been resolved:
bpf: Fix abuse of kprobe_write_ctx via freplace
uprobe programs are allowed to modify struct pt_regs.
Since the actual program type of uprobe is KPROBE, it can be abused to
modify struct pt_regs via kprobe+freplace when the kprobe attaches to
kernel functions.
For example,
SEC("?kprobe")
int kprobe(struct pt_regs *regs)
{
return 0;
}
SEC("?freplace")
int freplace_kprobe(struct pt_regs *regs)
{
regs->di = 0;
return 0;
}
freplace_kprobe prog will attach to kprobe prog.
kprobe prog will attach to a kernel function.
Without this patch, when the kernel function runs, its first arg will
always be set as 0 via the freplace_kprobe prog.
To fix the abuse of kprobe_write_ctx=true via kprobe+freplace, disallow
attaching freplace programs on kprobe programs with different
kprobe_write_ctx values.
Affected products
Linux · Linux