[PATCH] scripts/recordmcount: Fix uninitialized memory in file_append realloc

[Cuishuangjin <YS.cuishuangjin@h3c.com>]

The file_append() function uses realloc() to grow the buffer, but
realloc() doesn't zero the newly allocated memory. This can lead to
uninitialized data being written to the output file.

Fix this by:
1. Checking the realloc() return value for errors
2. Zeroing the newly allocated memory with memset()

Signed-off-by: cys43405 <YS.cuishuangjin@h3c.com>
---
scripts/recordmcount.c | 17 ++++++++++-------
1 file changed, 10 insertions(+), 7 deletions(-)

diff --git a/scripts/recordmcount.c b/scripts/recordmcount.c
index 3e4f54799cc0..754690887f66 100644
--- a/scripts/recordmcount.c
+++ b/scripts/recordmcount.c
@@ -111,6 +111,7 @@ static ssize_t uwrite(void const *const buf, size_t const count)
        size_t cnt = count;
        off_t idx = 0;
        void *p = NULL;
+       off_t old_size = 0;

        file_updated = 1;

@@ -118,18 +119,20 @@ static ssize_t uwrite(void const *const buf, size_t const count)
                off_t aoffset = (file_ptr + count) - file_end;

                if (aoffset > file_append_size) {
+                       old_size = file_append_size;
                        p = realloc(file_append, aoffset);
-                       if (!p)
+                       if (!p) {
                                free(file_append);
+                               perror("write");
+                               file_append_cleanup();
+                               mmap_cleanup();
+                               return -1;
+                       }
                        file_append = p;
                        file_append_size = aoffset;
+                       memset(file_append + old_size, 0, aoffset - old_size);
                }
-               if (!file_append) {
-                       perror("write");
-                       file_append_cleanup();
-                       mmap_cleanup();
-                       return -1;
-               }
+
                if (file_ptr < file_end) {
                        cnt = file_end - file_ptr;
                } else {
--
2.33.0
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