From 3f2989ed9570853aaf2b35edf96c07827a8b6bc0 Mon Sep 17 00:00:00 2001 From: Dan Carpenter Date: Fri, 8 Jul 2022 16:46:38 +0300 Subject: [PATCH] eeprom: idt_89hpesx: uninitialized data in idt_dbgfs_csr_write() [ Upstream commit 71d46f1ff2212ced4852c7e77c5176382a1bdcec ] The simple_write_to_buffer() function will return positive/success if it is able to write a single byte anywhere within the buffer. However that potentially leaves a lot of the buffer uninitialized. In this code it's better to return 0 if the offset is non-zero. This code is not written to support partial writes. And then return -EFAULT if the buffer is not completely initialized. Fixes: cfad6425382e ("eeprom: Add IDT 89HPESx EEPROM/CSR driver") Reviewed-by: Serge Semin Signed-off-by: Dan Carpenter Link: https://lore.kernel.org/r/Ysg1Pu/nzSMe3r1q@kili Signed-off-by: Greg Kroah-Hartman Signed-off-by: Sasha Levin --- drivers/misc/eeprom/idt_89hpesx.c | 8 ++++++-- 1 file changed, 6 insertions(+), 2 deletions(-) diff --git a/drivers/misc/eeprom/idt_89hpesx.c b/drivers/misc/eeprom/idt_89hpesx.c index b0cff4b..7f43074 100644 --- a/drivers/misc/eeprom/idt_89hpesx.c +++ b/drivers/misc/eeprom/idt_89hpesx.c @@ -909,14 +909,18 @@ static ssize_t idt_dbgfs_csr_write(struct file *filep, const char __user *ubuf, u32 csraddr, csrval; char *buf; + if (*offp) + return 0; + /* Copy data from User-space */ buf = kmalloc(count + 1, GFP_KERNEL); if (!buf) return -ENOMEM; - ret = simple_write_to_buffer(buf, count, offp, ubuf, count); - if (ret < 0) + if (copy_from_user(buf, ubuf, count)) { + ret = -EFAULT; goto free_buf; + } buf[count] = 0; /* Find position of colon in the buffer */ -- 2.7.4