[PATCH v3] blsuki: Fix grub_errno leakage in blsuki_is_default_entry()

[PATCH v3] blsuki: Fix grub_errno leakage in blsuki_is_default_entry()

[Michael Chang via Grub-devel]

The grub_strtol() call in blsuki_is_default_entry() can set grub_errno
to either GRUB_ERR_BAD_NUMBER or GRUB_ERR_OUT_OF_RANGE if the input
string is invalid or out of range.

This errno value is currently left uncleared, which can lead to
unexpected behavior in subsequent functions that rely on checking
current state of grub_errno.

Clear grub_errno and return false when grub_strtol() reports error. This
ensures that the error is handled and no grub_errno leakage.

Signed-off-by: Michael Chang <mchang@suse.com>
Reviewed-by: Sudhakar Kuppusamy <sudhakar@linux.ibm.com>
Reviewed-by: Avnish Chouhan <avnish@linux.ibm.com>
Reviewed-by: Alec Brown <alec.r.brown@oracle.com>
---
 grub-core/commands/blsuki.c | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/grub-core/commands/blsuki.c b/grub-core/commands/blsuki.c
index 21d767f05..9abb39a74 100644
--- a/grub-core/commands/blsuki.c
+++ b/grub-core/commands/blsuki.c
@@ -1510,6 +1510,12 @@ blsuki_is_default_entry (const char *def_entry, grub_blsuki_entry_t *entry, int
     return true;
 
   def_idx = grub_strtol (def_entry, &def_entry_end, 0);
+  if (grub_errno != GRUB_ERR_NONE)
+    {
+      grub_errno = GRUB_ERR_NONE;
+      return false;
+    }
+
   if (*def_entry_end != '\0' || def_idx < 0 || def_idx > GRUB_INT_MAX)
     return false;
 
-- 
2.51.1


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Re: [PATCH v3] blsuki: Fix grub_errno leakage in blsuki_is_default_entry()

[Daniel Kiper]

On Tue, Nov 18, 2025 at 04:04:48PM +0800, Michael Chang via Grub-devel wrote:
> The grub_strtol() call in blsuki_is_default_entry() can set grub_errno
> to either GRUB_ERR_BAD_NUMBER or GRUB_ERR_OUT_OF_RANGE if the input
> string is invalid or out of range.
>
> This errno value is currently left uncleared, which can lead to
> unexpected behavior in subsequent functions that rely on checking
> current state of grub_errno.
>
> Clear grub_errno and return false when grub_strtol() reports error. This
> ensures that the error is handled and no grub_errno leakage.
>
> Signed-off-by: Michael Chang <mchang@suse.com>
> Reviewed-by: Sudhakar Kuppusamy <sudhakar@linux.ibm.com>
> Reviewed-by: Avnish Chouhan <avnish@linux.ibm.com>
> Reviewed-by: Alec Brown <alec.r.brown@oracle.com>
> ---
>  grub-core/commands/blsuki.c | 6 ++++++
>  1 file changed, 6 insertions(+)
>
> diff --git a/grub-core/commands/blsuki.c b/grub-core/commands/blsuki.c
> index 21d767f05..9abb39a74 100644
> --- a/grub-core/commands/blsuki.c
> +++ b/grub-core/commands/blsuki.c
> @@ -1510,6 +1510,12 @@ blsuki_is_default_entry (const char *def_entry, grub_blsuki_entry_t *entry, int
>      return true;
>
>    def_idx = grub_strtol (def_entry, &def_entry_end, 0);
> +  if (grub_errno != GRUB_ERR_NONE)

This "if" is not really need. Please drop it. Everything will be caught
by the "if" below.

> +    {
> +      grub_errno = GRUB_ERR_NONE;
> +      return false;
> +    }
> +
>    if (*def_entry_end != '\0' || def_idx < 0 || def_idx > GRUB_INT_MAX)
>      return false;

Daniel

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