Subject: [PATCH v2] REFTABLE_REALLOC_ARRAY: remove this unsafe yet unused macro

From: "Lidong Yan via GitGitGadget" <[email-masked]>
Date: Fri, 09 May 2025 02:04:22 +0000

From: Lidong Yan <[email-masked]>

REFTABLE_REALLOC_ARRAY will cause memory leak if realloc failed.
Since it is unused, remove this unsafe macro.

Signed-off-by: Lidong Yan <[email-masked]>
---
    REFTABLE_REALLOC_ARRAY: fix potential memory leak if realloc failed
    
    REFTABLE_REALLOC_ARRAY doesn't free origin pointer when reftable_realloc
    failed. This leak can be fixed by add a free(x) before set x to NULL.

Published-As: https://github.com/gitgitgadget/git/releases/tag/pr-git-1955%2Fbrandb97%2Ffix-REFTABLE-REALLOC-leak-v2
Fetch-It-Via: git fetch https://github.com/gitgitgadget/git pr-git-1955/brandb97/fix-REFTABLE-REALLOC-leak-v2
Pull-Request: https://github.com/git/git/pull/1955

Range-diff vs v1:

 1:  4d786a0ec17 ! 1:  6cc191f9db8 REFTABLE_REALLOC_ARRAY: fix potential memory leak if realloc failed
     @@ Metadata
      Author: Lidong Yan <[email-masked]>
      
       ## Commit message ##
     -    REFTABLE_REALLOC_ARRAY: fix potential memory leak if realloc failed
     +    REFTABLE_REALLOC_ARRAY: remove this unsafe yet unused macro
      
     -    REFTABLE_REALLOC_ARRAY doesn't free origin pointer when reftable_realloc
     -    failed. This leak can be fixed by add a free(x) before set x to NULL.
     +    REFTABLE_REALLOC_ARRAY will cause memory leak if realloc failed.
     +    Since it is unused, remove this unsafe macro.
      
          Signed-off-by: Lidong Yan <[email-masked]>
      
       ## reftable/basics.h ##
      @@ reftable/basics.h: static inline int reftable_alloc_size(size_t nelem, size_t elsize, size_t *out)
     + 			(x) = reftable_malloc(alloc_size); \
       		} \
       	} while (0)
     - #define REFTABLE_CALLOC_ARRAY(x, alloc) (x) = reftable_calloc((alloc), sizeof(*(x)))
     +-#define REFTABLE_CALLOC_ARRAY(x, alloc) (x) = reftable_calloc((alloc), sizeof(*(x)))
      -#define REFTABLE_REALLOC_ARRAY(x, alloc) do { \
      -		size_t alloc_size; \
      -		if (reftable_alloc_size(sizeof(*(x)), (alloc), &alloc_size) < 0) { \
     @@ reftable/basics.h: static inline int reftable_alloc_size(size_t nelem, size_t el
      -		} else { \
      -			(x) = reftable_realloc((x), alloc_size); \
      -		} \
     -+#define REFTABLE_REALLOC_ARRAY(x, alloc)                                      \
     -+	do {                                                                  \
     -+		size_t alloc_size;                                            \
     -+		void *new_p;                                                  \
     -+		if (reftable_alloc_size(sizeof(*(x)), (alloc), &alloc_size) < \
     -+		    0) {                                                      \
     -+			goto cleanup;                                         \
     -+		} else {                                                      \
     -+			new_p = reftable_realloc((x), alloc_size);            \
     -+			if (!new_p) {                                         \
     -+				goto cleanup;                                 \
     -+			}                                                     \
     -+			(x) = new_p;                                          \
     -+		}                                                             \
     -+		break;                                                        \
     -+	cleanup:                                                              \
     -+		if (x)                                                        \
     -+			free(x);                                              \
     -+		errno = ENOMEM;                                               \
     -+		(x) = NULL;                                                   \
     - 	} while (0)
     +-	} while (0)
     ++#define REFTABLE_CALLOC_ARRAY(x, alloc) \
     ++	(x) = reftable_calloc((alloc), sizeof(*(x)))
       
       static inline void *reftable_alloc_grow(void *p, size_t nelem, size_t elsize,
     + 					size_t *allocp)

 reftable/basics.h | 12 ++----------
 1 file changed, 2 insertions(+), 10 deletions(-)

diff --git a/reftable/basics.h b/reftable/basics.h
index d8888c12629..667feffd935 100644
--- a/reftable/basics.h
+++ b/reftable/basics.h
@@ -199,16 +199,8 @@ static inline int reftable_alloc_size(size_t nelem, size_t elsize, size_t *out)
 			(x) = reftable_malloc(alloc_size); \
 		} \
 	} while (0)
-#define REFTABLE_CALLOC_ARRAY(x, alloc) (x) = reftable_calloc((alloc), sizeof(*(x)))
-#define REFTABLE_REALLOC_ARRAY(x, alloc) do { \
-		size_t alloc_size; \
-		if (reftable_alloc_size(sizeof(*(x)), (alloc), &alloc_size) < 0) { \
-			errno = ENOMEM; \
-			(x) = NULL; \
-		} else { \
-			(x) = reftable_realloc((x), alloc_size); \
-		} \
-	} while (0)
+#define REFTABLE_CALLOC_ARRAY(x, alloc) \
+	(x) = reftable_calloc((alloc), sizeof(*(x)))
 
 static inline void *reftable_alloc_grow(void *p, size_t nelem, size_t elsize,
 					size_t *allocp)

base-commit: 6f84262c44a89851c3ae5a6e4c1a9d06b2068d75
-- 
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