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authorGreg Kroah-Hartman <gregkh@linuxfoundation.org>2021-07-29 16:35:32 +0200
committerWolfram Sang <wsa@kernel.org>2021-08-10 22:54:10 +0200
commit86ff25ed6cd8240d18df58930bd8848b19fce308 (patch)
tree1b2325b3d9f8ce0546492daabb86144b4fdcf9fa
parentbba676cc0b6122a74fa2e246f38a6b05c6f95b36 (diff)
downloadlinux-86ff25ed6cd8240d18df58930bd8848b19fce308.tar.bz2
i2c: dev: zero out array used for i2c reads from userspace
If an i2c driver happens to not provide the full amount of data that a user asks for, it is possible that some uninitialized data could be sent to userspace. While all in-kernel drivers look to be safe, just be sure by initializing the buffer to zero before it is passed to the i2c driver so that any future drivers will not have this issue. Also properly copy the amount of data recvieved to the userspace buffer, as pointed out by Dan Carpenter. Reported-by: Eric Dumazet <edumazet@google.com> Cc: stable@vger.kernel.org Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Signed-off-by: Wolfram Sang <wsa@kernel.org>
-rw-r--r--drivers/i2c/i2c-dev.c5
1 files changed, 3 insertions, 2 deletions
diff --git a/drivers/i2c/i2c-dev.c b/drivers/i2c/i2c-dev.c
index cb64fe649390..77f576e51652 100644
--- a/drivers/i2c/i2c-dev.c
+++ b/drivers/i2c/i2c-dev.c
@@ -141,7 +141,7 @@ static ssize_t i2cdev_read(struct file *file, char __user *buf, size_t count,
if (count > 8192)
count = 8192;
- tmp = kmalloc(count, GFP_KERNEL);
+ tmp = kzalloc(count, GFP_KERNEL);
if (tmp == NULL)
return -ENOMEM;
@@ -150,7 +150,8 @@ static ssize_t i2cdev_read(struct file *file, char __user *buf, size_t count,
ret = i2c_master_recv(client, tmp, count);
if (ret >= 0)
- ret = copy_to_user(buf, tmp, count) ? -EFAULT : ret;
+ if (copy_to_user(buf, tmp, ret))
+ ret = -EFAULT;
kfree(tmp);
return ret;
}