Hi,
On Mon, Aug 04, 2025 at 08:40:27AM -0700, Kees Cook wrote:
> While the kernel command line is considered trusted in most environments,
> avoid writing 1 byte past the end of "acpiid" if the "str" argument is
> maximum length.
>
> Reported-by: Simcha Kosman <[email protected]>
> Closes:
> https://lore.kernel.org/all/as8p193mb2271c4b24bceda31830f37ae84...@as8p193mb2271.eurp193.prod.outlook.com
> Fixes: b6b26d86c61c ("iommu/amd: Add a length limitation for the ivrs_acpihid
> command-line parameter")
> Signed-off-by: Kees Cook <[email protected]>
> ---
> This was sent out before but it didn't end up on any public mailing list. My
> mistake!
> Cc: Joerg Roedel <[email protected]>
> Cc: Suravee Suthikulpanit <[email protected]>
> Cc: Will Deacon <[email protected]>
> Cc: Robin Murphy <[email protected]>
> Cc: <[email protected]>
> ---
> drivers/iommu/amd/init.c | 4 ++--
> 1 file changed, 2 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/iommu/amd/init.c b/drivers/iommu/amd/init.c
> index 7b5af6176de9..e11322d8d775 100644
> --- a/drivers/iommu/amd/init.c
> +++ b/drivers/iommu/amd/init.c
> @@ -3638,7 +3638,7 @@ static int __init parse_ivrs_acpihid(char *str)
> {
> u32 seg = 0, bus, dev, fn;
> char *hid, *uid, *p, *addr;
> - char acpiid[ACPIID_LEN] = {0};
> + char acpiid[ACPIID_LEN + 1] = { }; /* size with NUL terminator */
minor nits below,
s/NUL/NULL
and keeping "{0}" will be as per standard.
otherwise looks good!
Reviewed-by: Ankit Soni <[email protected]>
> int i;
>
> addr = strchr(str, '@');
> @@ -3664,7 +3664,7 @@ static int __init parse_ivrs_acpihid(char *str)
> /* We have the '@', make it the terminator to get just the acpiid */
> *addr++ = 0;
>
> - if (strlen(str) > ACPIID_LEN + 1)
> + if (strlen(str) > ACPIID_LEN)
> goto not_found;
>
> if (sscanf(str, "=%s", acpiid) != 1)
> --
> 2.34.1
>
