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Subject[tip: efi/urgent] efi/libstub: Handle unterminated cmdline
The following commit has been merged into the efi/urgent branch of tip:

Commit-ID: 8a8a3237a78cbc0557f0eb16a89f16d616323e99
Gitweb: https://git.kernel.org/tip/8a8a3237a78cbc0557f0eb16a89f16d616323e99
Author: Arvind Sankar <nivedita@alum.mit.edu>
AuthorDate: Thu, 13 Aug 2020 14:58:11 -04:00
Committer: Ard Biesheuvel <ardb@kernel.org>
CommitterDate: Thu, 20 Aug 2020 11:18:58 +02:00

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.

Cc: <stable@vger.kernel.org>
Signed-off-by: Arvind Sankar <nivedita@alum.mit.edu>
Link: https://lore.kernel.org/r/20200813185811.554051-4-nivedita@alum.mit.edu
Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
---
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 f53652a..f735db5 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;
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