Subject: [PATCH] wincred: avoid memory corruption

From: "Johannes Schindelin via GitGitGadget" <[email-masked]>
Date: Mon, 17 Nov 2025 20:39:44 +0000

From: David Macek <[email-masked]>

`wcsncpy_s()` wants to write the terminating null character so we need
to allocate one more space for it in the target memory block.

This should fix crashes when trying to read passwords.  When this
happened, the password/token wouldn't print out and Git would therefore
ask for a new password every time.

Signed-off-by: David Macek <[email-masked]>
Signed-off-by: Johannes Schindelin <[email-masked]>
---
    wincred: Avoid memory corruption
    
    This patch wants to be upstreamed...

Published-As: https://github.com/gitgitgadget/git/releases/tag/pr-2005%2Fdscho%2Fwincred-Avoid-memory-corruption-5856--v1
Fetch-It-Via: git fetch https://github.com/gitgitgadget/git pr-2005/dscho/wincred-Avoid-memory-corruption-5856--v1
Pull-Request: https://github.com/gitgitgadget/git/pull/2005

 contrib/credential/wincred/git-credential-wincred.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/contrib/credential/wincred/git-credential-wincred.c b/contrib/credential/wincred/git-credential-wincred.c
index 5683846b4b..73c2b9b72a 100644
--- a/contrib/credential/wincred/git-credential-wincred.c
+++ b/contrib/credential/wincred/git-credential-wincred.c
@@ -165,7 +165,7 @@ static void get_credential(void)
 			write_item("username", creds[i]->UserName,
 				creds[i]->UserName ? wcslen(creds[i]->UserName) : 0);
 			if (creds[i]->CredentialBlobSize > 0) {
-				secret = xmalloc(creds[i]->CredentialBlobSize);
+				secret = xmalloc(creds[i]->CredentialBlobSize + sizeof(WCHAR));
 				wcsncpy_s(secret, creds[i]->CredentialBlobSize, (LPCWSTR)creds[i]->CredentialBlob, creds[i]->CredentialBlobSize / sizeof(WCHAR));
 				line = wcstok_s(secret, L"\r\n", &remaining_lines);
 				write_item("password", line, line ? wcslen(line) : 0);

base-commit: 9a2fb147f2c61d0cab52c883e7e26f5b7948e3ed
-- 
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