linux-kernel - [PATCH 3/3] efi/libstub: Handle unterminated cmdline

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Date:   Thu, 13 Aug 2020 14:58:11 -0400
From:   Arvind Sankar <nivedita@...m.mit.edu>
To:     Ard Biesheuvel <ardb@...nel.org>, linux-efi@...r.kernel.org
Cc:     linux-kernel@...r.kernel.org
Subject: [PATCH 3/3] efi/libstub: Handle unterminated cmdline

Make the command line parsing more robust, by handling the case it is
not NUL-terminated.

Use strnlen instead of strlen, and make sure that the temporary copy is
NUL-terminated before parsing.

Signed-off-by: Arvind Sankar <nivedita@...m.mit.edu>
---
 drivers/firmware/efi/libstub/efi-stub-helper.c | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/drivers/firmware/efi/libstub/efi-stub-helper.c b/drivers/firmware/efi/libstub/efi-stub-helper.c
index f53652a3a106..fe5103086e27 100644
--- a/drivers/firmware/efi/libstub/efi-stub-helper.c
+++ b/drivers/firmware/efi/libstub/efi-stub-helper.c
@@ -194,12 +194,14 @@ efi_status_t efi_parse_options(char const *cmdline)
 	if (!cmdline)
 		return EFI_SUCCESS;
 
-	len = strlen(cmdline) + 1;
+	len = strnlen(cmdline, COMMAND_LINE_SIZE-1) + 1;
 	status = efi_bs_call(allocate_pool, EFI_LOADER_DATA, len, (void **)&buf);
 	if (status != EFI_SUCCESS)
 		return status;
 
-	str = skip_spaces(memcpy(buf, cmdline, len));
+	memcpy(buf, cmdline, len-1);
+	buf[len-1] = '\0';
+	str = skip_spaces(buf);
 
 	while (*str) {
 		char *param, *val;
-- 
2.26.2