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xtensa: simdisk: add input size check in proc_write_simdisk

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A malicious user could pass an arbitrarily bad value
to memdup_user_nul(), potentially causing kernel crash.

This follows the same pattern as commit ee76746387f6
("netdevsim: prevent bad user input in nsim_dev_health_break_write()")

Fixes: b6c7e873daf7 ("xtensa: ISS: add host file-based simulated disk")
Fixes: 16e5c1fc3604 ("convert a bunch of open-coded instances of memdup_user_nul()")
Cc: stable@vger.kernel.org
Signed-off-by: Miaoqian Lin <linmq006@gmail.com>
Message-Id: <20250829083015.1992751-1-linmq006@gmail.com>
Signed-off-by: Max Filippov <jcmvbkbc@gmail.com>
This commit is contained in:
Miaoqian Lin 2025-08-29 16:30:15 +08:00 committed by Max Filippov
parent 038d61fd64
commit 5d5f08fd0c
1 changed files with 5 additions and 1 deletions
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6
arch/xtensa/platforms/iss/simdisk.c
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@ -231,10 +231,14 @@ static ssize_t proc_read_simdisk(struct file *file, char __user *buf,
static ssize_t proc_write_simdisk(struct file *file, const char __user *buf,
size_t count, loff_t *ppos)
{
char *tmp = memdup_user_nul(buf, count);
char *tmp;
struct simdisk *dev = pde_data(file_inode(file));
int err;
if (count == 0 || count > PAGE_SIZE)
return -EINVAL;
tmp = memdup_user_nul(buf, count);
if (IS_ERR(tmp))
return PTR_ERR(tmp);