[PATCH 0/2] io_uring/net: fix bug in io_recvmsg_mshot_prep()

[PATCH 0/2] io_uring/net: fix bug in io_recvmsg_mshot_prep()

[Dan Carpenter]

The casting is problematic and could introduce an integer underflow
issue.

Dan Carpenter (2):
  io_uring/net: fix overflow check in io_recvmsg_mshot_prep()
  io_uring/net: remove unnecesary check

 io_uring/net.c | 6 ++----
 1 file changed, 2 insertions(+), 4 deletions(-)

-- 
2.43.0

[PATCH 1/2] io_uring/net: fix overflow check in io_recvmsg_mshot_prep()

[Dan Carpenter]

The "controllen" variable is type size_t (unsigned long).  Casting it
to int could lead to an integer underflow.

The check_add_overflow() function considers the type of the destination
which is type int.  If we add two positive values and the result cannot
fit in an integer then that's counted as an overflow.

However, if we cast "controllen" to an int and it turns negative, then
negative values *can* fit into an int type so there is no overflow.

Good: 100 + (unsigned long)-4 = 96  <-- overflow
 Bad: 100 + (int)-4 = 96 <-- no overflow

I deleted the cast of the sizeof() as well.  That's not a bug but the
cast is unnecessary.

Fixes: 9b0fc3c054ff ("io_uring: fix types in io_recvmsg_multishot_overflow")
Signed-off-by: Dan Carpenter <dan.carpenter@linaro.org>
---
 io_uring/net.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/io_uring/net.c b/io_uring/net.c
index 926d1fb0335d..da257bf429d5 100644
--- a/io_uring/net.c
+++ b/io_uring/net.c
@@ -559,10 +559,10 @@ static int io_recvmsg_mshot_prep(struct io_kiocb *req,
 
 		if (unlikely(namelen < 0))
 			return -EOVERFLOW;
-		if (check_add_overflow((int)sizeof(struct io_uring_recvmsg_out),
+		if (check_add_overflow(sizeof(struct io_uring_recvmsg_out),
 					namelen, &hdr))
 			return -EOVERFLOW;
-		if (check_add_overflow(hdr, (int)controllen, &hdr))
+		if (check_add_overflow(hdr, controllen, &hdr))
 			return -EOVERFLOW;
 
 		iomsg->namelen = namelen;
-- 
2.43.0

[PATCH 2/2] io_uring/net: remove unnecessary check

[Dan Carpenter]

"namelen" is type size_t so it can't be negative.

Signed-off-by: Dan Carpenter <dan.carpenter@linaro.org>
---
 io_uring/net.c | 2 --
 1 file changed, 2 deletions(-)

diff --git a/io_uring/net.c b/io_uring/net.c
index da257bf429d5..04a7426c80d2 100644
--- a/io_uring/net.c
+++ b/io_uring/net.c
@@ -557,8 +557,6 @@ static int io_recvmsg_mshot_prep(struct io_kiocb *req,
 			  (REQ_F_APOLL_MULTISHOT|REQ_F_BUFFER_SELECT)) {
 		int hdr;
 
-		if (unlikely(namelen < 0))
-			return -EOVERFLOW;
 		if (check_add_overflow(sizeof(struct io_uring_recvmsg_out),
 					namelen, &hdr))
 			return -EOVERFLOW;
-- 
2.43.0

Re: [PATCH 0/2] io_uring/net: fix bug in io_recvmsg_mshot_prep()

[Jens Axboe]

On Fri, 01 Mar 2024 18:28:40 +0300, Dan Carpenter wrote:
> The casting is problematic and could introduce an integer underflow
> issue.
> 
> Dan Carpenter (2):
>   io_uring/net: fix overflow check in io_recvmsg_mshot_prep()
>   io_uring/net: remove unnecesary check
> 
> [...]

Applied, thanks!

[1/2] io_uring/net: fix overflow check in io_recvmsg_mshot_prep()
      commit: a69d208854948bc8334a01bc17f13a06a5a977d2
[2/2] io_uring/net: remove unnecessary check
      commit: 789748af32c4a6f50db401d46e6a89ab28a6e3ac

Best regards,
-- 
Jens Axboe

Re: [PATCH 2/2] io_uring/net: remove unnecessary check

[Dan Carpenter]

On Fri, Mar 01, 2024 at 06:29:52PM +0300, Dan Carpenter wrote:
> "namelen" is type size_t so it can't be negative.
> 
> Signed-off-by: Dan Carpenter <dan.carpenter@linaro.org>
> ---

Jens applied Muhammad's patch so this part isn't required any more (and
would introduce a bug if it were).

regards,
dan carpenter

Re: [PATCH 2/2] io_uring/net: remove unnecessary check

[Jens Axboe]

On 3/1/24 9:56 AM, Dan Carpenter wrote:
> On Fri, Mar 01, 2024 at 06:29:52PM +0300, Dan Carpenter wrote:
>> "namelen" is type size_t so it can't be negative.
>>
>> Signed-off-by: Dan Carpenter <dan.carpenter@linaro.org>
>> ---
> 
> Jens applied Muhammad's patch so this part isn't required any more (and
> would introduce a bug if it were).

Yeah good point - thanks, I've dropped it.

-- 
Jens Axboe