[PATCH RESEND] kprobes: be more permissive when user specifies both symbol name and address

[PATCH RESEND] kprobes: be more permissive when user specifies both symbol name and address

[Jianyu Zhan]

Hi, I found that this patch wasn't merged into mainline during this merge
window(maybe it wasn't cooked in any tree), while it has been acked-by for
a couple of days.

Ingo, would you mind queueing this one? Thanks.

-----<8-----

Currently, if user specifies both symbol name and address, we just
bail out.

This might be too rude. This patch makes it give more tolerance.
If both are specified, check address first, if the symbol found
does not match the one user specify, print a waring. If not found,
return -ENOENT, because some symbols might have muplitple instances,
we don't bother to check symbol name.

Acked-by: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
Signed-off-by: Jianyu Zhan <nasa4836@gmail.com>
---
 Documentation/kprobes.txt |  4 +++-
 kernel/kprobes.c          | 32 +++++++++++++++++++++++++++++---
 2 files changed, 32 insertions(+), 4 deletions(-)

diff --git a/Documentation/kprobes.txt b/Documentation/kprobes.txt
index 4bbeca8..49af14e 100644
--- a/Documentation/kprobes.txt
+++ b/Documentation/kprobes.txt
@@ -358,7 +358,9 @@ to install a probepoint is known. This field is used to calculate the
 probepoint.
 
 3. Specify either the kprobe "symbol_name" OR the "addr". If both are
-specified, kprobe registration will fail with -EINVAL.
+specified, only check "addr", because some symbols might have muplitple
+instances. If neither is specified, kprobe registration will fail
+with -EINVAL.
 
 4. With CISC architectures (such as i386 and x86_64), the kprobes code
 does not validate if the kprobe.addr is at an instruction boundary.
diff --git a/kernel/kprobes.c b/kernel/kprobes.c
index 3214289..81d891b 100644
--- a/kernel/kprobes.c
+++ b/kernel/kprobes.c
@@ -1358,15 +1358,41 @@ static bool within_kprobe_blacklist(unsigned long addr)
 static kprobe_opcode_t *kprobe_addr(struct kprobe *p)
 {
 	kprobe_opcode_t *addr = p->addr;
+	char namebuf[KSYM_NAME_LEN];
+	const char *sym_name = NULL;
+	unsigned long offset;
 
-	if ((p->symbol_name && p->addr) ||
-	    (!p->symbol_name && !p->addr))
+	if (!p->symbol_name && !p->addr)
 		goto invalid;
 
-	if (p->symbol_name) {
+	/*
+	 * Some symbols might have muplitple instances,
+	 * so if both specified, only check address.
+	 */
+	if (unlikely(p->addr && p->symbol_name)) {
+		sym_name = kallsyms_lookup((unsigned long)(p->addr),
+				NULL, &offset, NULL, namebuf);
+		if (!sym_name)
+			return ERR_PTR(-ENOENT);
+
+		if (strncmp(sym_name, p->symbol_name, KSYM_NAME_LEN)
+				|| offset != p->offset) {
+			pr_err("Incorrect symbol or offset, should be "
+				"symbol=%s, offset=%ld.\n", sym_name, offset);
+			goto invalid;
+		}
+	} else if (p->symbol_name) {
+		/* Only symbol case */
 		kprobe_lookup_name(p->symbol_name, addr);
 		if (!addr)
 			return ERR_PTR(-ENOENT);
+	} else {
+		/*
+		 * Only address case.
+		 * Since we later will do sanity check of the
+		 * address range in check_kprobe_address_safe(),
+		 * do nothing here.
+		 */
 	}
 
 	addr = (kprobe_opcode_t *)(((char *)addr) + p->offset);
-- 
2.0.0

Re: [PATCH RESEND] kprobes: be more permissive when user specifies both symbol name and address

[Masami Hiramatsu]

(2014/06/20 16:34), Jianyu Zhan wrote:
> Hi, I found that this patch wasn't merged into mainline during this merge
> window(maybe it wasn't cooked in any tree), while it has been acked-by for
> a couple of days.
> 
> Ingo, would you mind queueing this one? Thanks.

Ping? I've already acked this.

> 
> -----<8-----
> 
> Currently, if user specifies both symbol name and address, we just
> bail out.
> 
> This might be too rude. This patch makes it give more tolerance.
> If both are specified, check address first, if the symbol found
> does not match the one user specify, print a waring. If not found,
> return -ENOENT, because some symbols might have muplitple instances,
> we don't bother to check symbol name.
> 
> Acked-by: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
> Signed-off-by: Jianyu Zhan <nasa4836@gmail.com>
> ---
>  Documentation/kprobes.txt |  4 +++-
>  kernel/kprobes.c          | 32 +++++++++++++++++++++++++++++---
>  2 files changed, 32 insertions(+), 4 deletions(-)
> 
> diff --git a/Documentation/kprobes.txt b/Documentation/kprobes.txt
> index 4bbeca8..49af14e 100644
> --- a/Documentation/kprobes.txt
> +++ b/Documentation/kprobes.txt
> @@ -358,7 +358,9 @@ to install a probepoint is known. This field is used to calculate the
>  probepoint.
>  
>  3. Specify either the kprobe "symbol_name" OR the "addr". If both are
> -specified, kprobe registration will fail with -EINVAL.
> +specified, only check "addr", because some symbols might have muplitple
> +instances. If neither is specified, kprobe registration will fail
> +with -EINVAL.
>  
>  4. With CISC architectures (such as i386 and x86_64), the kprobes code
>  does not validate if the kprobe.addr is at an instruction boundary.
> diff --git a/kernel/kprobes.c b/kernel/kprobes.c
> index 3214289..81d891b 100644
> --- a/kernel/kprobes.c
> +++ b/kernel/kprobes.c
> @@ -1358,15 +1358,41 @@ static bool within_kprobe_blacklist(unsigned long addr)
>  static kprobe_opcode_t *kprobe_addr(struct kprobe *p)
>  {
>  	kprobe_opcode_t *addr = p->addr;
> +	char namebuf[KSYM_NAME_LEN];
> +	const char *sym_name = NULL;
> +	unsigned long offset;
>  
> -	if ((p->symbol_name && p->addr) ||
> -	    (!p->symbol_name && !p->addr))
> +	if (!p->symbol_name && !p->addr)
>  		goto invalid;
>  
> -	if (p->symbol_name) {
> +	/*
> +	 * Some symbols might have muplitple instances,
> +	 * so if both specified, only check address.
> +	 */
> +	if (unlikely(p->addr && p->symbol_name)) {
> +		sym_name = kallsyms_lookup((unsigned long)(p->addr),
> +				NULL, &offset, NULL, namebuf);
> +		if (!sym_name)
> +			return ERR_PTR(-ENOENT);
> +
> +		if (strncmp(sym_name, p->symbol_name, KSYM_NAME_LEN)
> +				|| offset != p->offset) {
> +			pr_err("Incorrect symbol or offset, should be "
> +				"symbol=%s, offset=%ld.\n", sym_name, offset);
> +			goto invalid;
> +		}
> +	} else if (p->symbol_name) {
> +		/* Only symbol case */
>  		kprobe_lookup_name(p->symbol_name, addr);
>  		if (!addr)
>  			return ERR_PTR(-ENOENT);
> +	} else {
> +		/*
> +		 * Only address case.
> +		 * Since we later will do sanity check of the
> +		 * address range in check_kprobe_address_safe(),
> +		 * do nothing here.
> +		 */
>  	}
>  
>  	addr = (kprobe_opcode_t *)(((char *)addr) + p->offset);
> 


-- 
Masami HIRAMATSU
Software Platform Research Dept. Linux Technology Research Center
Hitachi, Ltd., Yokohama Research Laboratory
E-mail: masami.hiramatsu.pt@hitachi.com

Re: [PATCH RESEND] kprobes: be more permissive when user specifies both symbol name and address

[Ingo Molnar]

* Jianyu Zhan <nasa4836@gmail.com> wrote:

> Hi, I found that this patch wasn't merged into mainline during this merge
> window(maybe it wasn't cooked in any tree), while it has been acked-by for
> a couple of days.
> 
> Ingo, would you mind queueing this one? Thanks.
> 
> -----<8-----
> 
> Currently, if user specifies both symbol name and address, we just
> bail out.
> 
> This might be too rude. This patch makes it give more tolerance.
> If both are specified, check address first, if the symbol found
> does not match the one user specify, print a waring. If not found,
> return -ENOENT, because some symbols might have muplitple instances,
> we don't bother to check symbol name.
> 
> Acked-by: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
> Signed-off-by: Jianyu Zhan <nasa4836@gmail.com>
> ---
>  Documentation/kprobes.txt |  4 +++-
>  kernel/kprobes.c          | 32 +++++++++++++++++++++++++++++---
>  2 files changed, 32 insertions(+), 4 deletions(-)
> 
> diff --git a/Documentation/kprobes.txt b/Documentation/kprobes.txt
> index 4bbeca8..49af14e 100644
> --- a/Documentation/kprobes.txt
> +++ b/Documentation/kprobes.txt
> @@ -358,7 +358,9 @@ to install a probepoint is known. This field is used to calculate the
>  probepoint.
>  
>  3. Specify either the kprobe "symbol_name" OR the "addr". If both are
> -specified, kprobe registration will fail with -EINVAL.
> +specified, only check "addr", because some symbols might have muplitple
> +instances. If neither is specified, kprobe registration will fail
> +with -EINVAL.
>  
>  4. With CISC architectures (such as i386 and x86_64), the kprobes code
>  does not validate if the kprobe.addr is at an instruction boundary.
> diff --git a/kernel/kprobes.c b/kernel/kprobes.c
> index 3214289..81d891b 100644
> --- a/kernel/kprobes.c
> +++ b/kernel/kprobes.c
> @@ -1358,15 +1358,41 @@ static bool within_kprobe_blacklist(unsigned long addr)
>  static kprobe_opcode_t *kprobe_addr(struct kprobe *p)
>  {
>  	kprobe_opcode_t *addr = p->addr;
> +	char namebuf[KSYM_NAME_LEN];
> +	const char *sym_name = NULL;
> +	unsigned long offset;
>  
> -	if ((p->symbol_name && p->addr) ||
> -	    (!p->symbol_name && !p->addr))
> +	if (!p->symbol_name && !p->addr)
>  		goto invalid;
>  
> -	if (p->symbol_name) {
> +	/*
> +	 * Some symbols might have muplitple instances,

s/multiple

> +	 * so if both specified, only check address.

s/:

	 * so if both are specified, only check the address.

> +	} else {
> +		/*
> +		 * Only address case.
> +		 * Since we later will do sanity check of the

'will do a sanity check' or 'will do sanity checking'

Thanks,

	Ingo

Re: [PATCH RESEND] kprobes: be more permissive when user specifies both symbol name and address

[Jianyu Zhan]

Hi, Ingo,

Here is the new patch with typo fixed.

Thanks.

---8<---

Currently, if user specifies both symbol name and address, we just
bail out.

This might be too rude. This patch makes it give more tolerance.
If both are specified, check address first, if the symbol found
does not match the one user specify, print a waring. If not found,
return -ENOENT, because some symbols might have muplitple instances,
we don't bother to check symbol name.
---
 Documentation/kprobes.txt |  4 +++-
 kernel/kprobes.c          | 32 +++++++++++++++++++++++++++++---
 2 files changed, 32 insertions(+), 4 deletions(-)

diff --git a/Documentation/kprobes.txt b/Documentation/kprobes.txt
index 4bbeca8..663b5ad 100644
--- a/Documentation/kprobes.txt
+++ b/Documentation/kprobes.txt
@@ -358,7 +358,9 @@ to install a probepoint is known. This field is used to calculate the
 probepoint.
 
 3. Specify either the kprobe "symbol_name" OR the "addr". If both are
-specified, kprobe registration will fail with -EINVAL.
+specified, only check "addr", because some symbols might have multiple
+instances. If neither is specified, kprobe registration will fail
+with -EINVAL.
 
 4. With CISC architectures (such as i386 and x86_64), the kprobes code
 does not validate if the kprobe.addr is at an instruction boundary.
diff --git a/kernel/kprobes.c b/kernel/kprobes.c
index 734e9a7..9768608 100644
--- a/kernel/kprobes.c
+++ b/kernel/kprobes.c
@@ -1358,15 +1358,41 @@ static bool within_kprobe_blacklist(unsigned long addr)
 static kprobe_opcode_t *kprobe_addr(struct kprobe *p)
 {
 	kprobe_opcode_t *addr = p->addr;
+	char namebuf[KSYM_NAME_LEN];
+	const char *sym_name = NULL;
+	unsigned long offset;
 
-	if ((p->symbol_name && p->addr) ||
-	    (!p->symbol_name && !p->addr))
+	if (!p->symbol_name && !p->addr)
 		goto invalid;
 
-	if (p->symbol_name) {
+	/*
+	 * Some symbols might have multiple instances,
+	 * so if both are specified, only check address.
+	 */
+	if (unlikely(p->addr && p->symbol_name)) {
+		sym_name = kallsyms_lookup((unsigned long)(p->addr),
+				NULL, &offset, NULL, namebuf);
+		if (!sym_name)
+			return ERR_PTR(-ENOENT);
+
+		if (strncmp(sym_name, p->symbol_name, KSYM_NAME_LEN)
+				|| offset != p->offset) {
+			pr_err("Incorrect symbol or offset, should be "
+				"symbol=%s, offset=%ld.\n", sym_name, offset);
+			goto invalid;
+		}
+	} else if (p->symbol_name) {
+		/* Only symbol case */
 		kprobe_lookup_name(p->symbol_name, addr);
 		if (!addr)
 			return ERR_PTR(-ENOENT);
+	} else {
+		/*
+		 * Only address case.
+		 * Since we later will do a sanity check of the
+		 * address range in check_kprobe_address_safe(),
+		 * do nothing here.
+		 */
 	}
 
 	addr = (kprobe_opcode_t *)(((char *)addr) + p->offset);
-- 
2.0.0

Re: [PATCH RESEND] kprobes: be more permissive when user specifies both symbol name and address

[Jianyu Zhan]

Sorry for the noise,

plz add these Acked-by and Signed-off-by:

Acked-by: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
Signed-off-by: Jianyu Zhan <nasa4836@gmail.com>

Thanks,
Jianyu Zhan


On Tue, Jul 29, 2014 at 8:47 PM, Jianyu Zhan <nasa4836@gmail.com> wrote:
> Hi, Ingo,
>
> Here is the new patch with typo fixed.
>
> Thanks.
>
> ---8<---
>
> Currently, if user specifies both symbol name and address, we just
> bail out.
>
> This might be too rude. This patch makes it give more tolerance.
> If both are specified, check address first, if the symbol found
> does not match the one user specify, print a waring. If not found,
> return -ENOENT, because some symbols might have muplitple instances,
> we don't bother to check symbol name.
> ---
>  Documentation/kprobes.txt |  4 +++-
>  kernel/kprobes.c          | 32 +++++++++++++++++++++++++++++---
>  2 files changed, 32 insertions(+), 4 deletions(-)
>
> diff --git a/Documentation/kprobes.txt b/Documentation/kprobes.txt
> index 4bbeca8..663b5ad 100644
> --- a/Documentation/kprobes.txt
> +++ b/Documentation/kprobes.txt
> @@ -358,7 +358,9 @@ to install a probepoint is known. This field is used to calculate the
>  probepoint.
>
>  3. Specify either the kprobe "symbol_name" OR the "addr". If both are
> -specified, kprobe registration will fail with -EINVAL.
> +specified, only check "addr", because some symbols might have multiple
> +instances. If neither is specified, kprobe registration will fail
> +with -EINVAL.
>
>  4. With CISC architectures (such as i386 and x86_64), the kprobes code
>  does not validate if the kprobe.addr is at an instruction boundary.
> diff --git a/kernel/kprobes.c b/kernel/kprobes.c
> index 734e9a7..9768608 100644
> --- a/kernel/kprobes.c
> +++ b/kernel/kprobes.c
> @@ -1358,15 +1358,41 @@ static bool within_kprobe_blacklist(unsigned long addr)
>  static kprobe_opcode_t *kprobe_addr(struct kprobe *p)
>  {
>         kprobe_opcode_t *addr = p->addr;
> +       char namebuf[KSYM_NAME_LEN];
> +       const char *sym_name = NULL;
> +       unsigned long offset;
>
> -       if ((p->symbol_name && p->addr) ||
> -           (!p->symbol_name && !p->addr))
> +       if (!p->symbol_name && !p->addr)
>                 goto invalid;
>
> -       if (p->symbol_name) {
> +       /*
> +        * Some symbols might have multiple instances,
> +        * so if both are specified, only check address.
> +        */
> +       if (unlikely(p->addr && p->symbol_name)) {
> +               sym_name = kallsyms_lookup((unsigned long)(p->addr),
> +                               NULL, &offset, NULL, namebuf);
> +               if (!sym_name)
> +                       return ERR_PTR(-ENOENT);
> +
> +               if (strncmp(sym_name, p->symbol_name, KSYM_NAME_LEN)
> +                               || offset != p->offset) {
> +                       pr_err("Incorrect symbol or offset, should be "
> +                               "symbol=%s, offset=%ld.\n", sym_name, offset);
> +                       goto invalid;
> +               }
> +       } else if (p->symbol_name) {
> +               /* Only symbol case */
>                 kprobe_lookup_name(p->symbol_name, addr);
>                 if (!addr)
>                         return ERR_PTR(-ENOENT);
> +       } else {
> +               /*
> +                * Only address case.
> +                * Since we later will do a sanity check of the
> +                * address range in check_kprobe_address_safe(),
> +                * do nothing here.
> +                */
>         }
>
>         addr = (kprobe_opcode_t *)(((char *)addr) + p->offset);
> --
> 2.0.0
>

Re: [PATCH RESEND] kprobes: be more permissive when user specifies both symbol name and address

[Namhyung Kim]

Hi Jianyu,

On Tue, 29 Jul 2014 20:50:08 +0800, Jianyu Zhan wrote:
> Sorry for the noise,
>
> plz add these Acked-by and Signed-off-by:

I think you'd better to send it as a formal patch.

Thanks,
Namhyung


>
> Acked-by: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
> Signed-off-by: Jianyu Zhan <nasa4836@gmail.com>
>
> Thanks,
> Jianyu Zhan
>
>
> On Tue, Jul 29, 2014 at 8:47 PM, Jianyu Zhan <nasa4836@gmail.com> wrote:
>> Hi, Ingo,
>>
>> Here is the new patch with typo fixed.
>>
>> Thanks.
>>
>> ---8<---
>>
>> Currently, if user specifies both symbol name and address, we just
>> bail out.
>>
>> This might be too rude. This patch makes it give more tolerance.
>> If both are specified, check address first, if the symbol found
>> does not match the one user specify, print a waring. If not found,
>> return -ENOENT, because some symbols might have muplitple instances,
>> we don't bother to check symbol name.
>> ---
>>  Documentation/kprobes.txt |  4 +++-
>>  kernel/kprobes.c          | 32 +++++++++++++++++++++++++++++---
>>  2 files changed, 32 insertions(+), 4 deletions(-)
>>
>> diff --git a/Documentation/kprobes.txt b/Documentation/kprobes.txt
>> index 4bbeca8..663b5ad 100644
>> --- a/Documentation/kprobes.txt
>> +++ b/Documentation/kprobes.txt
>> @@ -358,7 +358,9 @@ to install a probepoint is known. This field is used to calculate the
>>  probepoint.
>>
>>  3. Specify either the kprobe "symbol_name" OR the "addr". If both are
>> -specified, kprobe registration will fail with -EINVAL.
>> +specified, only check "addr", because some symbols might have multiple
>> +instances. If neither is specified, kprobe registration will fail
>> +with -EINVAL.
>>
>>  4. With CISC architectures (such as i386 and x86_64), the kprobes code
>>  does not validate if the kprobe.addr is at an instruction boundary.
>> diff --git a/kernel/kprobes.c b/kernel/kprobes.c
>> index 734e9a7..9768608 100644
>> --- a/kernel/kprobes.c
>> +++ b/kernel/kprobes.c
>> @@ -1358,15 +1358,41 @@ static bool within_kprobe_blacklist(unsigned long addr)
>>  static kprobe_opcode_t *kprobe_addr(struct kprobe *p)
>>  {
>>         kprobe_opcode_t *addr = p->addr;
>> +       char namebuf[KSYM_NAME_LEN];
>> +       const char *sym_name = NULL;
>> +       unsigned long offset;
>>
>> -       if ((p->symbol_name && p->addr) ||
>> -           (!p->symbol_name && !p->addr))
>> +       if (!p->symbol_name && !p->addr)
>>                 goto invalid;
>>
>> -       if (p->symbol_name) {
>> +       /*
>> +        * Some symbols might have multiple instances,
>> +        * so if both are specified, only check address.
>> +        */
>> +       if (unlikely(p->addr && p->symbol_name)) {
>> +               sym_name = kallsyms_lookup((unsigned long)(p->addr),
>> +                               NULL, &offset, NULL, namebuf);
>> +               if (!sym_name)
>> +                       return ERR_PTR(-ENOENT);
>> +
>> +               if (strncmp(sym_name, p->symbol_name, KSYM_NAME_LEN)
>> +                               || offset != p->offset) {
>> +                       pr_err("Incorrect symbol or offset, should be "
>> +                               "symbol=%s, offset=%ld.\n", sym_name, offset);
>> +                       goto invalid;
>> +               }
>> +       } else if (p->symbol_name) {
>> +               /* Only symbol case */
>>                 kprobe_lookup_name(p->symbol_name, addr);
>>                 if (!addr)
>>                         return ERR_PTR(-ENOENT);
>> +       } else {
>> +               /*
>> +                * Only address case.
>> +                * Since we later will do a sanity check of the
>> +                * address range in check_kprobe_address_safe(),
>> +                * do nothing here.
>> +                */
>>         }
>>
>>         addr = (kprobe_opcode_t *)(((char *)addr) + p->offset);
>> --
>> 2.0.0
>>
> --
> To unsubscribe from this list: send the line "unsubscribe linux-doc" in
> the body of a message to majordomo@vger.kernel.org
> More majordomo info at  http://vger.kernel.org/majordomo-info.html

Re: Re: [PATCH RESEND] kprobes: be more permissive when user specifies both symbol name and address

[Masami Hiramatsu]

(2014/07/30 8:56), Namhyung Kim wrote:
> Hi Jianyu,
> 
> On Tue, 29 Jul 2014 20:50:08 +0800, Jianyu Zhan wrote:
>> Sorry for the noise,
>>
>> plz add these Acked-by and Signed-off-by:
> 
> I think you'd better to send it as a formal patch.

Agreed. Jianyu, please format it again. If you have a comment on it,
you can reply the patch mail.

Thank you,

> 
> Thanks,
> Namhyung
> 
> 
>>
>> Acked-by: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
>> Signed-off-by: Jianyu Zhan <nasa4836@gmail.com>
>>
>> Thanks,
>> Jianyu Zhan
>>
>>
>> On Tue, Jul 29, 2014 at 8:47 PM, Jianyu Zhan <nasa4836@gmail.com> wrote:
>>> Hi, Ingo,
>>>
>>> Here is the new patch with typo fixed.
>>>
>>> Thanks.
>>>
>>> ---8<---
>>>
>>> Currently, if user specifies both symbol name and address, we just
>>> bail out.
>>>
>>> This might be too rude. This patch makes it give more tolerance.
>>> If both are specified, check address first, if the symbol found
>>> does not match the one user specify, print a waring. If not found,
>>> return -ENOENT, because some symbols might have muplitple instances,
>>> we don't bother to check symbol name.
>>> ---
>>>  Documentation/kprobes.txt |  4 +++-
>>>  kernel/kprobes.c          | 32 +++++++++++++++++++++++++++++---
>>>  2 files changed, 32 insertions(+), 4 deletions(-)
>>>
>>> diff --git a/Documentation/kprobes.txt b/Documentation/kprobes.txt
>>> index 4bbeca8..663b5ad 100644
>>> --- a/Documentation/kprobes.txt
>>> +++ b/Documentation/kprobes.txt
>>> @@ -358,7 +358,9 @@ to install a probepoint is known. This field is used to calculate the
>>>  probepoint.
>>>
>>>  3. Specify either the kprobe "symbol_name" OR the "addr". If both are
>>> -specified, kprobe registration will fail with -EINVAL.
>>> +specified, only check "addr", because some symbols might have multiple
>>> +instances. If neither is specified, kprobe registration will fail
>>> +with -EINVAL.
>>>
>>>  4. With CISC architectures (such as i386 and x86_64), the kprobes code
>>>  does not validate if the kprobe.addr is at an instruction boundary.
>>> diff --git a/kernel/kprobes.c b/kernel/kprobes.c
>>> index 734e9a7..9768608 100644
>>> --- a/kernel/kprobes.c
>>> +++ b/kernel/kprobes.c
>>> @@ -1358,15 +1358,41 @@ static bool within_kprobe_blacklist(unsigned long addr)
>>>  static kprobe_opcode_t *kprobe_addr(struct kprobe *p)
>>>  {
>>>         kprobe_opcode_t *addr = p->addr;
>>> +       char namebuf[KSYM_NAME_LEN];
>>> +       const char *sym_name = NULL;
>>> +       unsigned long offset;
>>>
>>> -       if ((p->symbol_name && p->addr) ||
>>> -           (!p->symbol_name && !p->addr))
>>> +       if (!p->symbol_name && !p->addr)
>>>                 goto invalid;
>>>
>>> -       if (p->symbol_name) {
>>> +       /*
>>> +        * Some symbols might have multiple instances,
>>> +        * so if both are specified, only check address.
>>> +        */
>>> +       if (unlikely(p->addr && p->symbol_name)) {
>>> +               sym_name = kallsyms_lookup((unsigned long)(p->addr),
>>> +                               NULL, &offset, NULL, namebuf);
>>> +               if (!sym_name)
>>> +                       return ERR_PTR(-ENOENT);
>>> +
>>> +               if (strncmp(sym_name, p->symbol_name, KSYM_NAME_LEN)
>>> +                               || offset != p->offset) {
>>> +                       pr_err("Incorrect symbol or offset, should be "
>>> +                               "symbol=%s, offset=%ld.\n", sym_name, offset);
>>> +                       goto invalid;
>>> +               }
>>> +       } else if (p->symbol_name) {
>>> +               /* Only symbol case */
>>>                 kprobe_lookup_name(p->symbol_name, addr);
>>>                 if (!addr)
>>>                         return ERR_PTR(-ENOENT);
>>> +       } else {
>>> +               /*
>>> +                * Only address case.
>>> +                * Since we later will do a sanity check of the
>>> +                * address range in check_kprobe_address_safe(),
>>> +                * do nothing here.
>>> +                */
>>>         }
>>>
>>>         addr = (kprobe_opcode_t *)(((char *)addr) + p->offset);
>>> --
>>> 2.0.0
>>>
>> --
>> To unsubscribe from this list: send the line "unsubscribe linux-doc" in
>> the body of a message to majordomo@vger.kernel.org
>> More majordomo info at  http://vger.kernel.org/majordomo-info.html
> --
> To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
> the body of a message to majordomo@vger.kernel.org
> More majordomo info at  http://vger.kernel.org/majordomo-info.html
> Please read the FAQ at  http://www.tux.org/lkml/
> 


-- 
Masami HIRAMATSU
Software Platform Research Dept. Linux Technology Research Center
Hitachi, Ltd., Yokohama Research Laboratory
E-mail: masami.hiramatsu.pt@hitachi.com