glibc/glibc-RHEL-46736-6.patch

commit 9c0d6f7a1046aba111e25e34ec07242853e859dc
Author: Joseph Myers <josmyers@redhat.com>
Date:   Thu Sep 5 11:16:59 2024 +0000

    Fix memory leak on freopen error return (bug 32140)
    
    As reported in bug 32140, freopen leaks the FILE object when it
    returns NULL: there is no valid use of the FILE * pointer (including
    passing to freopen again or to fclose) after such an error return, so
    the underlying object should be freed.  Add code to free it.
    
    Note 1: while I think it's clear from the relevant standards that the
    object should be freed and the FILE * can't be used after the call in
    this case (the stream is closed, which ends the lifetime of the FILE),
    it's entirely possible that some existing code does in fact try to use
    the existing FILE * in some way and could be broken by this change.
    (Though the most common case for freopen may be stdin / stdout /
    stderr, which _IO_deallocate_file explicitly checks for and does not
    deallocate.)
    
    Note 2: the deallocation is only done in the _IO_IS_FILEBUF case.
    Other kinds of streams bypass all the freopen logic handling closing
    the file, meaning a call to _IO_deallocate_file would neither be safe
    (the FILE might still be linked into the list of all open FILEs) nor
    sufficient (other internal memory allocations associated with the file
    would not have been freed).  I think the validity of freopen for any
    other kind of stream will need clarifying with the Austin Group, but
    if it is valid in any such case (where "valid" means "not undefined
    behavior so required to close the stream" rather than "required to
    successfully associate the stream with the new file in cases where
    fopen would work"), more significant changes would be needed to ensure
    the stream gets fully closed.
    
    Tested for x86_64.

diff --git a/libio/freopen.c b/libio/freopen.c
index bed034d89441f200..03f8961a61b12e80 100644
--- a/libio/freopen.c
+++ b/libio/freopen.c
@@ -114,5 +114,7 @@ freopen (const char *filename, const char *mode, FILE *fp)
 
 end:
   _IO_release_lock (fp);
+  if (result == NULL && (fp->_flags & _IO_IS_FILEBUF) != 0)
+    _IO_deallocate_file (fp);
   return result;
 }
diff --git a/libio/freopen64.c b/libio/freopen64.c
index 9a314c65c1d8a5a4..abcbd80a5bd92e69 100644
--- a/libio/freopen64.c
+++ b/libio/freopen64.c
@@ -94,5 +94,7 @@ freopen64 (const char *filename, const char *mode, FILE *fp)
 
 end:
   _IO_release_lock (fp);
+  if (result == NULL && (fp->_flags & _IO_IS_FILEBUF) != 0)
+    _IO_deallocate_file (fp);
   return result;
 }
diff --git a/stdio-common/Makefile b/stdio-common/Makefile
index 5eddc4bfbf4e7fb9..bd3c785537ba0330 100644
--- a/stdio-common/Makefile
+++ b/stdio-common/Makefile
@@ -251,7 +251,9 @@ ifeq (yes,$(build-shared))
 ifneq ($(PERL),no)
 tests-special += \
   $(objpfx)tst-freopen2-mem.out \
+  $(objpfx)tst-freopen3-mem.out \
   $(objpfx)tst-freopen64-2-mem.out \
+  $(objpfx)tst-freopen64-3-mem.out \
   $(objpfx)tst-getline-enomem-mem.out \
   $(objpfx)tst-getline-mem.out \
   $(objpfx)tst-printf-bz18872-mem.out \
@@ -264,8 +266,12 @@ tests-special += \
 generated += \
   tst-freopen2-mem.out \
   tst-freopen2.mtrace \
+  tst-freopen3-mem.out \
+  tst-freopen3.mtrace \
   tst-freopen64-2-mem.out \
   tst-freopen64-2.mtrace \
+  tst-freopen64-3-mem.out \
+  tst-freopen64-3.mtrace \
   tst-getline-enomem-mem.out \
   tst-getline-enomem.mtrace \
   tst-getline-mem.out \
@@ -344,6 +350,12 @@ tst-freopen2-ENV = \
 tst-freopen64-2-ENV = \
   MALLOC_TRACE=$(objpfx)tst-freopen64-2.mtrace \
   LD_PRELOAD=$(common-objpfx)malloc/libc_malloc_debug.so
+tst-freopen3-ENV = \
+  MALLOC_TRACE=$(objpfx)tst-freopen3.mtrace \
+  LD_PRELOAD=$(common-objpfx)malloc/libc_malloc_debug.so
+tst-freopen64-3-ENV = \
+  MALLOC_TRACE=$(objpfx)tst-freopen64-3.mtrace \
+  LD_PRELOAD=$(common-objpfx)malloc/libc_malloc_debug.so
 
 $(objpfx)tst-unbputc.out: tst-unbputc.sh $(objpfx)tst-unbputc
 	$(SHELL) $< $(common-objpfx) '$(test-program-prefix)'; \
diff --git a/stdio-common/tst-freopen3-main.c b/stdio-common/tst-freopen3-main.c
index 5107e1f98e189e4b..990a6e5921843793 100644
--- a/stdio-common/tst-freopen3-main.c
+++ b/stdio-common/tst-freopen3-main.c
@@ -18,6 +18,7 @@
 
 #include <errno.h>
 #include <fcntl.h>
+#include <mcheck.h>
 #include <stdio.h>
 #include <stdlib.h>
 
@@ -48,6 +49,7 @@
 int
 do_test (void)
 {
+  mtrace ();
   struct support_descriptors *fds;
   char *temp_dir = support_create_temp_directory ("tst-freopen3");
   char *file1 = xasprintf ("%s/file1", temp_dir);