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

[Michael Chang via Grub-devel <grub-devel@gnu.org>]

The grub_strtol() call in blsuki_is_default_entry() can set grub_errno
to GRUB_ERR_BAD_NUMBER if the input string cannot be converted into any
valid digits.

This errno value is currently left uncleared, which can lead to
unexpected behavior in subsequent logic that tests the result of a
function by checking grub_errno.

Clear grub_errno and return false when GRUB_ERR_BAD_NUMBER is set, as
this specific error should be ignored in this context.

Signed-off-by: Michael Chang <mchang@suse.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..df25b6fbc 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_BAD_NUMBER)
+    {
+      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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