+cc Kees Cook
Hi Barry,
On 31/10/24 09:01, Barry Song wrote:
On Thu, Oct 31, 2024 at 6:55 PM Maíra Canal <mcanal@xxxxxxxxxx> wrote:
Hi Barry,
On 30/10/24 20:07, Barry Song wrote:
On Thu, Oct 31, 2024 at 2:03 AM Maíra Canal <mcanal@xxxxxxxxxx> wrote:
Replace strcpy() with strscpy() in mm/huge_memory.c
strcpy() has been deprecated because it is generally unsafe, so help to
eliminate it from the kernel source.
Link: https://github.com/KSPP/linux/issues/88
Signed-off-by: Maíra Canal <mcanal@xxxxxxxxxx>
---
mm/huge_memory.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)
diff --git a/mm/huge_memory.c b/mm/huge_memory.c
index f92068864469..8f41a694433c 100644
--- a/mm/huge_memory.c
+++ b/mm/huge_memory.c
@@ -989,7 +989,7 @@ static int __init setup_thp_anon(char *str)
if (!str || strlen(str) + 1 > PAGE_SIZE)
goto err;
- strcpy(str_dup, str);
+ strscpy(str_dup, str);
What is the difference between strcpy and strscpy without a size parameter?
we have already a check and goto err. strcpy() is entirely safe.
if (!str || strlen(str) + 1 > PAGE_SIZE)
goto err;
My understanding is that we don't need this patch.
strcpy() is a deprecated interface [1]. From the GitHub issue I linked
in the commit description, Kees states: "A lot of kernel code is still
using strcpy(). While the CONFIG_FORTIFY_SOURCE wrapper macros tend to
make its use mostly safe, it would be nice to eliminate the function
from the kernel entirely."
I don't see any value added here since strscpy() has no size parameter and
As `str_dup` is a sized buffer, we don't need to specify the size
parameter.
we have checked strlen(str) + 1 > PAGE_SIZE to avoid parsing any pointless
bootcmd longer than PAGE_SIZE.
From my point of view, this is an extra layer of safety. A developer
could change `str_dup` to SZ_4K and leave PAGE_SIZE in the check. This
could pass by in a review and we would have a check that allows strings
bigger than the destination buffer in systems using 16KB pages.
But see that `split_huge_pages_write` uses `strcpy` without any checks.
I can remove the internal check from `setup_thp_anon` if you feel it
would be more suitable.
Best Regards,
- Maíra
> > But I have no objection to this patch if other people like it.
[1] https://www.kernel.org/doc/html/latest/process/deprecated.html#strcpy
Best Regards,
- Maíra
always = huge_anon_orders_always;
madvise = huge_anon_orders_madvise;
@@ -4175,7 +4175,7 @@ static ssize_t split_huge_pages_write(struct file *file, const char __user *buf,
tok = strsep(&buf, ",");
if (tok) {
- strcpy(file_path, tok);
+ strscpy(file_path, tok);
} else {
ret = -EINVAL;
goto out;
--
2.46.2
Thanks
barry
