Re: [PATCH net] net/rose: prevent integer overflows in rose_setsockopt()

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On 2025/1/16 07:29, David Laight wrote:
On Wed, 15 Jan 2025 08:42:20 -0800
Nikita Zhandarovich <n.zhandarovich@xxxxxxxxxx> wrote:

In case of possible unpredictably large arguments passed to
rose_setsockopt() and multiplied by extra values on top of that,
integer overflows may occur.

Do the safest minimum and fix these issues by checking the
contents of 'opt' and returning -EINVAL if they are too large. Also,
switch to unsigned int and remove useless check for negative 'opt'
in ROSE_IDLE case.

Found by Linux Verification Center (linuxtesting.org) with static
analysis tool SVACE.

Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2")
Cc: stable@xxxxxxxxxxxxxxx
Signed-off-by: Nikita Zhandarovich <n.zhandarovich@xxxxxxxxxx>
---
  net/rose/af_rose.c | 16 ++++++++--------
  1 file changed, 8 insertions(+), 8 deletions(-)

diff --git a/net/rose/af_rose.c b/net/rose/af_rose.c
index 59050caab65c..72c65d938a15 100644
--- a/net/rose/af_rose.c
+++ b/net/rose/af_rose.c
@@ -397,15 +397,15 @@ static int rose_setsockopt(struct socket *sock, int level, int optname,
  {
  	struct sock *sk = sock->sk;
  	struct rose_sock *rose = rose_sk(sk);
-	int opt;
+	unsigned int opt;
if (level != SOL_ROSE)
  		return -ENOPROTOOPT;
- if (optlen < sizeof(int))
+	if (optlen < sizeof(unsigned int))
  		return -EINVAL;
- if (copy_from_sockptr(&opt, optval, sizeof(int)))
+	if (copy_from_sockptr(&opt, optval, sizeof(unsigned int)))
Shouldn't all those be 'sizeof (opt)' ?

	David

  		return -EFAULT;
switch (optname) {
@@ -414,31 +414,31 @@ static int rose_setsockopt(struct socket *sock, int level, int optname,
  		return 0;
case ROSE_T1:
-		if (opt < 1)
+		if (opt < 1 || opt > UINT_MAX / HZ)

'rose->t1' is unsigned long, how about 'opt > ULONG_MAX / HZ' ?

BTW, I think only in 32bit or 16bit machine when 'sizeof(int) == sizeof(unsigned long)',
this integer overflows may occur..

Su Hui

  			return -EINVAL;
  		rose->t1 = opt * HZ;
  		return 0;
case ROSE_T2:
-		if (opt < 1)
+		if (opt < 1 || opt > UINT_MAX / HZ)
  			return -EINVAL;
  		rose->t2 = opt * HZ;
  		return 0;
case ROSE_T3:
-		if (opt < 1)
+		if (opt < 1 || opt > UINT_MAX / HZ)
  			return -EINVAL;
  		rose->t3 = opt * HZ;
  		return 0;
case ROSE_HOLDBACK:
-		if (opt < 1)
+		if (opt < 1 || opt > UINT_MAX / HZ)
  			return -EINVAL;
  		rose->hb = opt * HZ;
  		return 0;
case ROSE_IDLE:
-		if (opt < 0)
+		if (opt > UINT_MAX / (60 * HZ))
  			return -EINVAL;
  		rose->idle = opt * 60 * HZ;
  		return 0;





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