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 --- arch/xtensa/platforms/iss/simdisk.c | 6 +++++- 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/arch/xtensa/platforms/iss/simdisk.c b/arch/xtensa/platforms/iss/simdisk.c index 6ed009318d24..3cafc8feddee 100644 --- a/arch/xtensa/platforms/iss/simdisk.c +++ b/arch/xtensa/platforms/iss/simdisk.c @@ -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);