strncpy() is an ambiguous and potentially dangerous interface [1]. We should prefer more robust and less ambiguous alternatives.
@query is marked as __nonstring and doesn't need to be NUL-terminated. Since we are doing a string to memory copy, we can use the aptly named "strtomem" -- specifically, the "pad" variant to also ensure NUL-padding throughout the destination buffer. Link: https://www.kernel.org/doc/html/latest/process/deprecated.html#strncpy-on-nul-terminated-strings [1] Link: https://manpages.debian.org/testing/linux-manual-4.8/strscpy.9.en.html [2] Link: https://github.com/KSPP/linux/issues/90 Cc: linux-hardening@vger.kernel.org Reviewed-by: Kees Cook <keesc...@chromium.org> Signed-off-by: Justin Stitt <justinst...@google.com> --- Changes in v3: - Prefer strtomem_pad (thanks Bjorn) - Reword commit message (thanks Bjorn) - Carry over Kees' RB as this new version is functionally the same and matches the same spirit of v2 - Link to v2: https://lore.kernel.org/r/20240318-strncpy-drivers-soc-qcom-cmd-db-c-v2-1-8f6ebf1bd...@google.com Changes in v2: - use strtomem instead of memcpy (thanks Kees) - Link to v1: https://lore.kernel.org/r/20240314-strncpy-drivers-soc-qcom-cmd-db-c-v1-1-70f5d5e70...@google.com --- Note: build-tested only. Found with: $ rg "strncpy\(" --- drivers/soc/qcom/cmd-db.c | 7 +------ 1 file changed, 1 insertion(+), 6 deletions(-) diff --git a/drivers/soc/qcom/cmd-db.c b/drivers/soc/qcom/cmd-db.c index a5fd68411bed..d51ae99d9c02 100644 --- a/drivers/soc/qcom/cmd-db.c +++ b/drivers/soc/qcom/cmd-db.c @@ -147,12 +147,7 @@ static int cmd_db_get_header(const char *id, const struct entry_header **eh, if (ret) return ret; - /* - * Pad out query string to same length as in DB. NOTE: the output - * query string is not necessarily '\0' terminated if it bumps up - * against the max size. That's OK and expected. - */ - strncpy(query, id, sizeof(query)); + strtomem_pad(query, id, 0); for (i = 0; i < MAX_SLV_ID; i++) { rsc_hdr = &cmd_db_header->header[i]; --- base-commit: fe46a7dd189e25604716c03576d05ac8a5209743 change-id: 20240314-strncpy-drivers-soc-qcom-cmd-db-c-284f3abaabb8 Best regards, -- Justin Stitt <justinst...@google.com>
