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Re: [PATCH][2.6.25-rc2-mm1] fix a null pointer bug in register_kretprobe
- From: Ananth N Mavinakayanahalli <ananth at in dot ibm dot com>
- To: Masami Hiramatsu <mhiramat at redhat dot com>
- Cc: LKML <linux-kernel at vger dot kernel dot org>, Andrew Morton <akpm at linux-foundation dot org>, systemtap-ml <systemtap at sources dot redhat dot com>, Jim Keniston <jkenisto at us dot ibm dot com>
- Date: Tue, 4 Mar 2008 07:43:15 +0530
- Subject: Re: [PATCH][2.6.25-rc2-mm1] fix a null pointer bug in register_kretprobe
- References: <47CC7B1C.1060305@redhat.com>
- Reply-to: ananth at in dot ibm dot com
On Mon, Mar 03, 2008 at 05:26:36PM -0500, Masami Hiramatsu wrote:
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>
> Fix a bug in regiseter_kretprobe() which does not check
> rp->kp.symbol_name == NULL before calling kprobe_lookup_name.
>
> For maintainability, this introduces kprobe_addr helper function which
> resolves addr field. It is used by register_kprobe and register_kretprobe.
>
> Signed-off-by: Masami Hiramatsu <mhiramat@redhat.com>
> CC: Ananth N Mavinakayanahalli <ananth@in.ibm.com>
> CC: Jim Keniston <jkenisto@us.ibm.com>
Acked-by: Ananth N Mavinakayanahalli <ananth@in.ibm.com>
Thanks Masami!
> ---
> kernel/kprobes.c | 43 ++++++++++++++++++++++++++-----------------
> 1 file changed, 26 insertions(+), 17 deletions(-)
>
> Index: 2.6.25-rc2-mm1/kernel/kprobes.c
> ===================================================================
> --- 2.6.25-rc2-mm1.orig/kernel/kprobes.c 2008-02-18 11:37:18.000000000 -0500
> +++ 2.6.25-rc2-mm1/kernel/kprobes.c 2008-02-18 11:37:18.000000000 -0500
> @@ -498,27 +498,36 @@ static int __kprobes in_kprobes_function
> return 0;
> }
>
> +/*
> + * If we have a symbol_name argument, look it up and add the offset field
> + * to it. This way, we can specify a relative address to a symbol.
> + */
> +static kprobe_opcode_t __kprobes *kprobe_addr(struct kprobe *p)
> +{
> + kprobe_opcode_t *addr = p->addr;
> + if (p->symbol_name) {
> + if (addr)
> + return NULL;
> + kprobe_lookup_name(p->symbol_name, addr);
> + }
> +
> + if (!addr)
> + return NULL;
> + return (kprobe_opcode_t *)(((char *)addr) + p->offset);
> +}
> +
> static int __kprobes __register_kprobe(struct kprobe *p,
> unsigned long called_from)
> {
> int ret = 0;
> struct kprobe *old_p;
> struct module *probed_mod;
> + kprobe_opcode_t *addr;
>
> - /*
> - * If we have a symbol_name argument look it up,
> - * and add it to the address. That way the addr
> - * field can either be global or relative to a symbol.
> - */
> - if (p->symbol_name) {
> - if (p->addr)
> - return -EINVAL;
> - kprobe_lookup_name(p->symbol_name, p->addr);
> - }
> -
> - if (!p->addr)
> + addr = kprobe_addr(p);
> + if (!addr)
> return -EINVAL;
> - p->addr = (kprobe_opcode_t *)(((char *)p->addr)+ p->offset);
> + p->addr = addr;
>
> if (!kernel_text_address((unsigned long) p->addr) ||
> in_kprobes_functions((unsigned long) p->addr))
> @@ -722,12 +731,12 @@ int __kprobes register_kretprobe(struct
> int ret = 0;
> struct kretprobe_instance *inst;
> int i;
> - void *addr = rp->kp.addr;
> + void *addr;
>
> if (kretprobe_blacklist_size) {
> - if (addr == NULL)
> - kprobe_lookup_name(rp->kp.symbol_name, addr);
> - addr += rp->kp.offset;
> + addr = kprobe_addr(&rp->kp);
> + if (!addr)
> + return -EINVAL;
>
> for (i = 0; kretprobe_blacklist[i].name != NULL; i++) {
> if (kretprobe_blacklist[i].addr == addr)
> --
> Masami Hiramatsu
>
> Software Engineer
> Hitachi Computer Products (America) Inc.
> Software Solutions Division
>
> e-mail: mhiramat@redhat.com
>