diff mbox series

[v2] x86/mm: Fix use of uninitialized buffer in sme_enable()

Message ID 20230306160656.14844-1-n.zhandarovich@fintech.ru
State New
Headers
Series [v2] x86/mm: Fix use of uninitialized buffer in sme_enable() |

Commit Message

Nikita Zhandarovich March 6, 2023, 4:06 p.m. UTC 
  cmdline_find_option() may fail before doing any initialization of
buffer array. This may lead to unpredictable results when the same
buffer is used later in calls to strncmp() function.
Fix the issue by returning early if cmdline_find_option() returns -1.

Found by Linux Verification Center (linuxtesting.org) with static analysis
tool SVACE.

Fixes: aca20d546214 ("x86/mm: Add support to make use of Secure Memory Encryption")
Signed-off-by: Nikita Zhandarovich <n.zhandarovich@fintech.ru>
---
v2: per Borislav Petkov's <bp@alien8.de> remarks:
- return early if cmdline_find_options() fails with -1 instead of zeroing out
buffer;
- use correct Fixes: commit hash

 arch/x86/mm/mem_encrypt_identity.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

Comments

Tom Lendacky March 13, 2023, 12:49 p.m. UTC | #1 
On 3/6/23 10:06, Nikita Zhandarovich wrote:
> cmdline_find_option() may fail before doing any initialization of
> buffer array. This may lead to unpredictable results when the same
> buffer is used later in calls to strncmp() function.
> Fix the issue by returning early if cmdline_find_option() returns -1.
> 
> Found by Linux Verification Center (linuxtesting.org) with static analysis
> tool SVACE.
> 
> Fixes: aca20d546214 ("x86/mm: Add support to make use of Secure Memory Encryption")
> Signed-off-by: Nikita Zhandarovich <n.zhandarovich@fintech.ru>

Acked-by: Tom Lendacky <thomas.lendacky@amd.com>

> ---
> v2: per Borislav Petkov's <bp@alien8.de> remarks:
> - return early if cmdline_find_options() fails with -1 instead of zeroing out
> buffer;
> - use correct Fixes: commit hash
> 
>   arch/x86/mm/mem_encrypt_identity.c | 3 ++-
>   1 file changed, 2 insertions(+), 1 deletion(-)
> 
> diff --git a/arch/x86/mm/mem_encrypt_identity.c b/arch/x86/mm/mem_encrypt_identity.c
> index 88cccd65029d..c6efcf559d88 100644
> --- a/arch/x86/mm/mem_encrypt_identity.c
> +++ b/arch/x86/mm/mem_encrypt_identity.c
> @@ -600,7 +600,8 @@ void __init sme_enable(struct boot_params *bp)
>   	cmdline_ptr = (const char *)((u64)bp->hdr.cmd_line_ptr |
>   				     ((u64)bp->ext_cmd_line_ptr << 32));
>   
> -	cmdline_find_option(cmdline_ptr, cmdline_arg, buffer, sizeof(buffer));
> +	if (cmdline_find_option(cmdline_ptr, cmdline_arg, buffer, sizeof(buffer)) < 0)
> +		return;
>   
>   	if (!strncmp(buffer, cmdline_on, sizeof(buffer)))
>   		sme_me_mask = me_mask;
diff mbox series

Patch

diff --git a/arch/x86/mm/mem_encrypt_identity.c b/arch/x86/mm/mem_encrypt_identity.c
index 88cccd65029d..c6efcf559d88 100644
--- a/arch/x86/mm/mem_encrypt_identity.c
+++ b/arch/x86/mm/mem_encrypt_identity.c
@@ -600,7 +600,8 @@  void __init sme_enable(struct boot_params *bp)
 	cmdline_ptr = (const char *)((u64)bp->hdr.cmd_line_ptr |
 				     ((u64)bp->ext_cmd_line_ptr << 32));
 
-	cmdline_find_option(cmdline_ptr, cmdline_arg, buffer, sizeof(buffer));
+	if (cmdline_find_option(cmdline_ptr, cmdline_arg, buffer, sizeof(buffer)) < 0)
+		return;
 
 	if (!strncmp(buffer, cmdline_on, sizeof(buffer)))
 		sme_me_mask = me_mask;