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* [PATCH] Fix null pointer dereference in vector_user_bpf
@ 2020-06-11  2:40 Gaurav Singh
  0 siblings, 0 replies; 5+ messages in thread
From: Gaurav Singh @ 2020-06-11  2:40 UTC (permalink / raw)
  To: gaurav1086, Jeff Dike, Richard Weinberger, Anton Ivanov,
	Alexei Starovoitov, Daniel Borkmann, Martin KaFai Lau, Song Liu,
	Yonghong Song, Andrii Nakryiko, John Fastabend, KP Singh,
	Alex Dewar, open list:USER-MODE LINUX (UML),
	open list, open list:BPF (Safe dynamic programs and tools),
	open list:BPF (Safe dynamic programs and tools)

The bpf_prog is being checked for !NULL after uml_kmalloc but
later its used directly for example:
bpf_prog->filter = bpf and is also later returned upon success.
Fix this, do a NULL check and return right away.

Signed-off-by: Gaurav Singh <gaurav1086@gmail.com>
---
 arch/um/drivers/vector_user.c | 8 +++++---
 1 file changed, 5 insertions(+), 3 deletions(-)

diff --git a/arch/um/drivers/vector_user.c b/arch/um/drivers/vector_user.c
index aa28e9eecb7b..71d043ae306f 100644
--- a/arch/um/drivers/vector_user.c
+++ b/arch/um/drivers/vector_user.c
@@ -730,10 +730,12 @@ void *uml_vector_user_bpf(char *filename)
 		return false;
 	}
 	bpf_prog = uml_kmalloc(sizeof(struct sock_fprog), UM_GFP_KERNEL);
-	if (bpf_prog != NULL) {
-		bpf_prog->len = statbuf.st_size / sizeof(struct sock_filter);
-		bpf_prog->filter = NULL;
+	if (bpf_prog == NULL) {
+		printk(KERN_ERR "Failed to allocate bpf prog buffer");
+		return NULL;
 	}
+	bpf_prog->len = statbuf.st_size / sizeof(struct sock_filter);
+	bpf_prog->filter = NULL;
 	ffd = os_open_file(filename, of_read(OPENFLAGS()), 0);
 	if (ffd < 0) {
 		printk(KERN_ERR "Error %d opening bpf file", -errno);
-- 
2.17.1


^ permalink raw reply related	[flat|nested] 5+ messages in thread

* Re: [PATCH] Fix null pointer dereference in vector_user_bpf
  2020-06-14  1:19 Gaurav Singh
@ 2020-06-14  6:38 ` Anton Ivanov
  0 siblings, 0 replies; 5+ messages in thread
From: Anton Ivanov @ 2020-06-14  6:38 UTC (permalink / raw)
  To: Gaurav Singh, Jeff Dike, Richard Weinberger, Alexei Starovoitov,
	Daniel Borkmann, Martin KaFai Lau, Song Liu, Yonghong Song,
	Andrii Nakryiko, John Fastabend, KP Singh, Alex Dewar,
	Marc-André Lureau, open list:USER-MODE LINUX (UML),
	open list, open list:BPF (Safe dynamic programs and tools),
	open list:BPF (Safe dynamic programs and tools)

On 14/06/2020 02:19, Gaurav Singh wrote:
> The bpf_prog is being checked for !NULL after uml_kmalloc
> but later its used directly for example:
> bpf_prog->filter = bpf and is also later returned upon
> success. Fix this, do a NULL check and return right away.
> 
> Signed-off-by: Gaurav Singh <gaurav1086@gmail.com>
> ---
>   arch/um/drivers/vector_user.c | 8 +++++---
>   1 file changed, 5 insertions(+), 3 deletions(-)
> 
> diff --git a/arch/um/drivers/vector_user.c b/arch/um/drivers/vector_user.c
> index c4a0f26b2824..0e6d6717bf73 100644
> --- a/arch/um/drivers/vector_user.c
> +++ b/arch/um/drivers/vector_user.c
> @@ -789,10 +789,12 @@ void *uml_vector_user_bpf(char *filename)
>   		return false;
>   	}
>   	bpf_prog = uml_kmalloc(sizeof(struct sock_fprog), UM_GFP_KERNEL);
> -	if (bpf_prog != NULL) {
> -		bpf_prog->len = statbuf.st_size / sizeof(struct sock_filter);
> -		bpf_prog->filter = NULL;
> +	if (bpf_prog == NULL) {
> +		printk(KERN_ERR "Failed to allocate bpf prog buffer");
> +		return NULL;
>   	}
> +	bpf_prog->len = statbuf.st_size / sizeof(struct sock_filter);
> +	bpf_prog->filter = NULL;
>   	ffd = os_open_file(filename, of_read(OPENFLAGS()), 0);
>   	if (ffd < 0) {
>   		printk(KERN_ERR "Error %d opening bpf file", -errno);
> 

Acked-By: Anton Ivanov <anton.ivanov@cambridgegreys.com>
-- 
Anton R. Ivanov
Cambridgegreys Limited. Registered in England. Company Number 10273661
https://www.cambridgegreys.com/

^ permalink raw reply	[flat|nested] 5+ messages in thread

* [PATCH] Fix null pointer dereference in vector_user_bpf
@ 2020-06-14  1:19 Gaurav Singh
  2020-06-14  6:38 ` Anton Ivanov
  0 siblings, 1 reply; 5+ messages in thread
From: Gaurav Singh @ 2020-06-14  1:19 UTC (permalink / raw)
  To: gaurav1086, Jeff Dike, Richard Weinberger, Anton Ivanov,
	Alexei Starovoitov, Daniel Borkmann, Martin KaFai Lau, Song Liu,
	Yonghong Song, Andrii Nakryiko, John Fastabend, KP Singh,
	Alex Dewar, Marc-André Lureau,
	open list:USER-MODE LINUX (UML),
	open list, open list:BPF (Safe dynamic programs and tools),
	open list:BPF (Safe dynamic programs and tools)

The bpf_prog is being checked for !NULL after uml_kmalloc
but later its used directly for example: 
bpf_prog->filter = bpf and is also later returned upon
success. Fix this, do a NULL check and return right away.

Signed-off-by: Gaurav Singh <gaurav1086@gmail.com>
---
 arch/um/drivers/vector_user.c | 8 +++++---
 1 file changed, 5 insertions(+), 3 deletions(-)

diff --git a/arch/um/drivers/vector_user.c b/arch/um/drivers/vector_user.c
index c4a0f26b2824..0e6d6717bf73 100644
--- a/arch/um/drivers/vector_user.c
+++ b/arch/um/drivers/vector_user.c
@@ -789,10 +789,12 @@ void *uml_vector_user_bpf(char *filename)
 		return false;
 	}
 	bpf_prog = uml_kmalloc(sizeof(struct sock_fprog), UM_GFP_KERNEL);
-	if (bpf_prog != NULL) {
-		bpf_prog->len = statbuf.st_size / sizeof(struct sock_filter);
-		bpf_prog->filter = NULL;
+	if (bpf_prog == NULL) {
+		printk(KERN_ERR "Failed to allocate bpf prog buffer");
+		return NULL;
 	}
+	bpf_prog->len = statbuf.st_size / sizeof(struct sock_filter);
+	bpf_prog->filter = NULL;
 	ffd = os_open_file(filename, of_read(OPENFLAGS()), 0);
 	if (ffd < 0) {
 		printk(KERN_ERR "Error %d opening bpf file", -errno);
-- 
2.17.1


^ permalink raw reply related	[flat|nested] 5+ messages in thread

* Re: [PATCH] Fix null pointer dereference in vector_user_bpf
  2020-06-10  3:43 Gaurav Singh
@ 2020-06-10  5:53 ` Greg KH
  0 siblings, 0 replies; 5+ messages in thread
From: Greg KH @ 2020-06-10  5:53 UTC (permalink / raw)
  To: Gaurav Singh
  Cc: Jeff Dike, Richard Weinberger, Anton Ivanov, Alexei Starovoitov,
	Daniel Borkmann, Martin KaFai Lau, Song Liu, Yonghong Song,
	Andrii Nakryiko, John Fastabend, KP Singh, Alex Dewar,
	open list:USER-MODE LINUX (UML),
	open list, open list:BPF (Safe dynamic programs and tools),
	open list:BPF (Safe dynamic programs and tools)

On Tue, Jun 09, 2020 at 11:43:00PM -0400, Gaurav Singh wrote:
> Signed-off-by: Gaurav Singh <gaurav1086@gmail.com>
> 
> The bpf_prog is being checked for !NULL after uml_kmalloc but
> later its used directly for example: 
> bpf_prog->filter = bpf and is also later returned upon success.
> Fix this, do a NULL check and return right away.
> 
> ---
>  arch/um/drivers/vector_user.c | 8 +++++---
>  1 file changed, 5 insertions(+), 3 deletions(-)

No signed-off-by?

^ permalink raw reply	[flat|nested] 5+ messages in thread

* [PATCH] Fix null pointer dereference in vector_user_bpf
@ 2020-06-10  3:43 Gaurav Singh
  2020-06-10  5:53 ` Greg KH
  0 siblings, 1 reply; 5+ messages in thread
From: Gaurav Singh @ 2020-06-10  3:43 UTC (permalink / raw)
  To: gaurav1086, Jeff Dike, Richard Weinberger, Anton Ivanov,
	Alexei Starovoitov, Daniel Borkmann, Martin KaFai Lau, Song Liu,
	Yonghong Song, Andrii Nakryiko, John Fastabend, KP Singh,
	Alex Dewar, open list:USER-MODE LINUX (UML),
	open list, open list:BPF (Safe dynamic programs and tools),
	open list:BPF (Safe dynamic programs and tools)

Signed-off-by: Gaurav Singh <gaurav1086@gmail.com>

The bpf_prog is being checked for !NULL after uml_kmalloc but
later its used directly for example: 
bpf_prog->filter = bpf and is also later returned upon success.
Fix this, do a NULL check and return right away.

---
 arch/um/drivers/vector_user.c | 8 +++++---
 1 file changed, 5 insertions(+), 3 deletions(-)

diff --git a/arch/um/drivers/vector_user.c b/arch/um/drivers/vector_user.c
index aa28e9eecb7b..71d043ae306f 100644
--- a/arch/um/drivers/vector_user.c
+++ b/arch/um/drivers/vector_user.c
@@ -730,10 +730,12 @@ void *uml_vector_user_bpf(char *filename)
 		return false;
 	}
 	bpf_prog = uml_kmalloc(sizeof(struct sock_fprog), UM_GFP_KERNEL);
-	if (bpf_prog != NULL) {
-		bpf_prog->len = statbuf.st_size / sizeof(struct sock_filter);
-		bpf_prog->filter = NULL;
+	if (bpf_prog == NULL) {
+		printk(KERN_ERR "Failed to allocate bpf prog buffer");
+		return NULL;
 	}
+	bpf_prog->len = statbuf.st_size / sizeof(struct sock_filter);
+	bpf_prog->filter = NULL;
 	ffd = os_open_file(filename, of_read(OPENFLAGS()), 0);
 	if (ffd < 0) {
 		printk(KERN_ERR "Error %d opening bpf file", -errno);
-- 
2.17.1


^ permalink raw reply related	[flat|nested] 5+ messages in thread

end of thread, other threads:[~2020-06-14  7:03 UTC | newest]

Thread overview: 5+ messages (download: mbox.gz / follow: Atom feed)
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2020-06-11  2:40 [PATCH] Fix null pointer dereference in vector_user_bpf Gaurav Singh
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2020-06-14  1:19 Gaurav Singh
2020-06-14  6:38 ` Anton Ivanov
2020-06-10  3:43 Gaurav Singh
2020-06-10  5:53 ` Greg KH

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