Subject: important potential issues found by covscan in diffutils-3.7 on fedora

From: than <[email-masked]>
Date: Wed, 24 Mar 2021 15:07:15 +0100

Dear diffutil devs,

Covscan found 10important potentialin diffutils-3.7 on fedora. The 
Coverity covscan result is attached below. It could be that some of them 
are false positive but it's worth checking the coverity covscan result.

Thanks!

Best Regards,

Than

List of Defects:
Error: COMPILER_WARNING (CWE-758): [#def1]
diffutils-3.7/lib/exclude.c:636:18: warning[-Wstringop-overflow=]: 
writing 1 byte into a region of size 0
#  636 |   buf[buf_count] = line_end;
#      |                  ^
#  634|
#  635|     buf = xrealloc (buf, buf_count + 1);
#  636|->   buf[buf_count] = line_end;
#  637|     lim = buf + buf_count + ! (buf_count == 0 || buf[buf_count - 
1] == line_end);
#  638|

Error: RESOURCE_LEAK (CWE-772): [#def2]
diffutils-3.7/lib/freopen-safer.c:42: open_fn: Returning handle opened 
by "open". [Note: The source code implementation of the function has 
been overridden by a user model.]
diffutils-3.7/lib/freopen-safer.c:42: var_assign: Assigning: "value" = 
handle returned from "open("/dev/null", 0)".
diffutils-3.7/lib/freopen-safer.c:52: leaked_handle: Handle variable 
"value" going out of scope leaks the handle.
#   50|         return false;
#   51|       }
#   52|->   return true;
#   53|   }
#   54|

Error: CPPCHECK_WARNING (CWE-401): [#def3]
diffutils-3.7/lib/malloca.c:67: error[memleak]: Memory leak: mem
#   65|             ((small_t *) p)[-1] = p - mem;
#   66|             /* p  sa_alignment_max mod 2*sa_alignment_max.  */
#   67|->           return p;
#   68|           }
#   69|       }

Error: RESOURCE_LEAK (CWE-772): [#def4]
diffutils-3.7/lib/regex_internal.c:1684: alloc_fn: Storage is returned 
from allocation function "calloc".
diffutils-3.7/lib/regex_internal.c:1684: var_assign: Assigning: 
"newstate" = storage returned from "calloc(112UL, 1UL)".
diffutils-3.7/lib/regex_internal.c:1687: noescape: Resource 
"&newstate->nodes" is not freed or pointed-to in "re_node_set_init_copy".
diffutils-3.7/lib/regex_internal.c:1734: noescape: Resource 
"&newstate->nodes" is not freed or pointed-to in "re_node_set_remove_at".
diffutils-3.7/lib/regex_internal.c:1734: noescape: Resource 
"&newstate->nodes" is not freed or pointed-to in "re_node_set_remove_at".
diffutils-3.7/lib/regex_internal.c:1734: noescape: Resource 
"&newstate->nodes" is not freed or pointed-to in "re_node_set_remove_at".
diffutils-3.7/lib/regex_internal.c:1727: leaked_storage: Variable 
"newstate" going out of scope leaks the storage it points to.
# 1725|             if (re_node_set_init_copy (newstate->entrance_nodes, 
nodes)
# 1726|             != REG_NOERROR)
# 1727|->         return NULL;
# 1728|             nctx_nodes = 0;
# 1729|             newstate->has_constraint = 1;

Error: BAD_FREE (CWE-763): [#def5]
diffutils-3.7/src/analyze.c:691: offset_free: "free" frees address 
offset from "cmp->file[f].linbuf".
#  689|       {
#  690|         free (cmp->file[f].equivs);
#  691|->       free (cmp->file[f].linbuf + cmp->file[f].linbuf_base);
#  692|       }
#  693|

Error: RESOURCE_LEAK (CWE-772): [#def6]
diffutils-3.7/src/diff3.c:783: alloc_fn: Storage is returned from 
allocation function "create_diff3_block".
diffutils-3.7/src/diff3.c:783: var_assign: Assigning: "result" = storage 
returned from "create_diff3_block(low[0], high[0], low[1], high[1], 
lowc, highc)".
diffutils-3.7/src/diff3.c:798: leaked_storage: Variable "result" going 
out of scope leaks the storage it points to.
#  796|                     D_LENARRAY (result, FILEC) + result_offset,
#  797|                     D_NUMLINES (ptr, FC)))
#  798|->       return 0;
#  799|         }
#  800|

Error: RESOURCE_LEAK (CWE-772): [#def7]
diffutils-3.7/src/diff3.c:783: alloc_fn: Storage is returned from 
allocation function "create_diff3_block".
diffutils-3.7/src/diff3.c:783: var_assign: Assigning: "result" = storage 
returned from "create_diff3_block(low[0], high[0], low[1], high[1], 
lowc, highc)".
diffutils-3.7/src/diff3.c:827: leaked_storage: Variable "result" going 
out of scope leaks the storage it points to.
#  825|                   D_LENARRAY (result, FILE0 + d) + result_offset,
#  826|                   D_NUMLINES (ptr, FO)))
#  827|->         return 0;
#  828|
#  829|         /* Catch the lines between here and the next diff */

Error: RESOURCE_LEAK (CWE-772): [#def8]
diffutils-3.7/src/ifdef.c:368: alloc_fn: Storage is returned from 
allocation function "xmalloc".
diffutils-3.7/src/ifdef.c:368: var_assign: Assigning: "format" = storage 
returned from "xmalloc(spec_prefix_len + pI_len + 2UL)".
diffutils-3.7/src/ifdef.c:370: var_assign: Assigning: "p" = "format".
diffutils-3.7/src/ifdef.c:371: noescape: Resource "format" is not freed 
or pointed-to in "memcpy". [Note: The source code implementation of the 
function has been overridden by a builtin model.]
diffutils-3.7/src/ifdef.c:372: noescape: Resource "format + 
spec_prefix_len" is not freed or pointed-to in "memcpy". [Note: The 
source code implementation of the function has been overridden by a 
builtin model.]
diffutils-3.7/src/ifdef.c:375: noescape: Resource "format" is not freed 
or pointed-to in "fprintf". [Note: The source code implementation of the 
function has been overridden by a builtin model.]
diffutils-3.7/src/ifdef.c:379: leaked_storage: Variable "p" going out of 
scope leaks the storage it points to.
diffutils-3.7/src/ifdef.c:379: leaked_storage: Variable "format" going 
out of scope leaks the storage it points to.
#  377|           free (format);
#  378|   #endif
#  379|->       }
#  380|         }
#  381|         break;

Error: RESOURCE_LEAK (CWE-772): [#def9]
diffutils-3.7/src/sdiff.c:1166: alloc_fn: Storage is returned from 
allocation function "xmalloc".
diffutils-3.7/src/sdiff.c:1166: var_assign: Assigning: "buf" = storage 
returned from "xmalloc(strlen(dir) + 1UL + 5UL + 6UL + 1UL)".
diffutils-3.7/src/sdiff.c:1168: noescape: Resource "buf" is not freed or 
pointed-to in "sprintf". [Note: The source code implementation of the 
function has been overridden by a builtin model.]
diffutils-3.7/src/sdiff.c:1169: noescape: Resource "buf" is not freed or 
pointed-to in "mkstemp".
diffutils-3.7/src/sdiff.c:1172: leaked_storage: Variable "buf" going out 
of scope leaks the storage it points to.
# 1170|     if (0 <= fd)
# 1171|       tmpname = buf;
# 1172|->   return fd;
# 1173|   }

Error: RESOURCE_LEAK (CWE-772): [#def10]
diffutils-3.7/src/util.c:594: alloc_fn: Storage is returned from 
allocation function "xstrdup".
diffutils-3.7/src/util.c:594: var_assign: Assigning: "color_buf" = 
storage returned from "xstrdup(p)".
diffutils-3.7/src/util.c:594: var_assign: Assigning: "buf" = "color_buf".
diffutils-3.7/src/util.c:702: leaked_storage: Variable "buf" going out 
of scope leaks the storage it points to.
diffutils-3.7/src/util.c:702: leaked_storage: Variable "color_buf" going 
out of scope leaks the storage it points to.
#  700|         colors_enabled = false;
#  701|       }
#  702|-> }
#  703|
#  704|   static void