Re: [PATCH] Kprobes: Verify probepoint in register_jprobe()

[Paulo Marques <pmarques@grupopie.com>]

Luca Falavigna wrote:
> [...]
>  int register_jprobe(struct jprobe *jp)
>  {
> -	/* Todo: Verify probepoint is a function entry point */
> +	unsigned long size, offset;
> +	char *modname, namebuf[KSYM_NAME_LEN+1];
> +	
> +	kallsyms_lookup((unsigned long)jp->kp.addr, &size,
> +			&offset, &modname, namebuf);
> +	
> +	if(unlikely(offset))
> +		return -EINVAL;

Hmmm, kallsyms_lookup might return NULL if either the address is not 
found or CONFIG_KALLSYMS is not set, and in this case "offset" is not 
initialized at all before this test.

We should either fail in this case, or accept the address as valid 
without confirmation. I don't have sufficient knowledge about kprobes to 
advise either way, but a test should be made nevertheless (or we could 
just initialize "offset" to 0, if we want to accept the address without 
confirmation).

-- 
Paulo Marques - www.grupopie.com

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