6.12-stable review patch. If anyone has any objections, please let me know.
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From: Miaoqian Lin linmq006@gmail.com
commit 5d5f08fd0cd970184376bee07d59f635c8403f63 upstream.
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 Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- arch/xtensa/platforms/iss/simdisk.c | 6 +++++- 1 file changed, 5 insertions(+), 1 deletion(-)
--- a/arch/xtensa/platforms/iss/simdisk.c +++ b/arch/xtensa/platforms/iss/simdisk.c @@ -230,10 +230,14 @@ static ssize_t proc_read_simdisk(struct 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);