From: Kees Cook Date: Mon, 4 Aug 2025 15:40:27 +0000 (-0700) Subject: iommu/amd: Avoid stack buffer overflow from kernel cmdline X-Git-Url: https://www.infradead.org/git/?a=commitdiff_plain;h=8503d0fcb1086a7cfe26df67ca4bd9bd9e99bdec;p=users%2Fjedix%2Flinux-maple.git iommu/amd: Avoid stack buffer overflow from kernel cmdline 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 Closes: https://lore.kernel.org/all/AS8P193MB2271C4B24BCEDA31830F37AE84A52@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 Reviewed-by: Ankit Soni Link: https://lore.kernel.org/r/20250804154023.work.970-kees@kernel.org Signed-off-by: Joerg Roedel --- diff --git a/drivers/iommu/amd/init.c b/drivers/iommu/amd/init.c index 7b5af6176de99..8de689b2c5ed5 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 NULL terminator */ 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)