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| author | Siddhesh Poyarekar <siddhesh@sourceware.org> | 2024-08-13 21:08:49 -0400 |
|---|---|---|
| committer | Siddhesh Poyarekar <siddhesh@sourceware.org> | 2024-08-28 15:58:45 -0400 |
| commit | a500b48bd2a6401de442c00f433079d24331dbb6 (patch) | |
| tree | b2db22818bc60aaee4a128046b7b5ed8d6014c73 /libio | |
| parent | 70939528c67507f12d6d41423b7fac25153a6dce (diff) | |
| download | glibc-a500b48bd2a6401de442c00f433079d24331dbb6.zip glibc-a500b48bd2a6401de442c00f433079d24331dbb6.tar.gz glibc-a500b48bd2a6401de442c00f433079d24331dbb6.tar.bz2 | |
ungetc: Fix backup buffer leak on program exit [BZ #27821]
If a file descriptor is left unclosed and is cleaned up by _IO_cleanup
on exit, its backup buffer remains unfreed, registering as a leak in
valgrind. This is not strictly an issue since (1) the program should
ideally be closing the stream once it's not in use and (2) the program
is about to exit anyway, so keeping the backup buffer around a wee bit
longer isn't a real problem. Free it anyway to keep valgrind happy
when the streams in question are the standard ones, i.e. stdout, stdin
or stderr.
Also, the _IO_have_backup macro checks for _IO_save_base,
which is a roundabout way to check for a backup buffer instead of
directly looking for _IO_backup_base. The roundabout check breaks when
the main get area has not been used and user pushes a char into the
backup buffer with ungetc. Fix this to use the _IO_backup_base
directly.
Signed-off-by: Siddhesh Poyarekar <siddhesh@sourceware.org>
Reviewed-by: Carlos O'Donell <carlos@redhat.com>
(cherry picked from commit 3e1d8d1d1dca24ae90df2ea826a8916896fc7e77)
Diffstat (limited to 'libio')
| -rw-r--r-- | libio/genops.c | 6 | ||||
| -rw-r--r-- | libio/libioP.h | 4 |
2 files changed, 8 insertions, 2 deletions
diff --git a/libio/genops.c b/libio/genops.c index 4f5c613..bb1d959 100644 --- a/libio/genops.c +++ b/libio/genops.c @@ -789,6 +789,12 @@ _IO_unbuffer_all (void) legacy = 1; #endif + /* Free up the backup area if it was ever allocated. */ + if (_IO_have_backup (fp)) + _IO_free_backup_area (fp); + if (fp->_mode > 0 && _IO_have_wbackup (fp)) + _IO_free_wbackup_area (fp); + if (! (fp->_flags & _IO_UNBUFFERED) /* Iff stream is un-orientated, it wasn't used. */ && (legacy || fp->_mode != 0)) diff --git a/libio/libioP.h b/libio/libioP.h index 1af287b..616253f 100644 --- a/libio/libioP.h +++ b/libio/libioP.h @@ -577,8 +577,8 @@ extern void _IO_old_init (FILE *fp, int flags) __THROW; ((__fp)->_wide_data->_IO_write_base \ = (__fp)->_wide_data->_IO_write_ptr = __p, \ (__fp)->_wide_data->_IO_write_end = (__ep)) -#define _IO_have_backup(fp) ((fp)->_IO_save_base != NULL) -#define _IO_have_wbackup(fp) ((fp)->_wide_data->_IO_save_base != NULL) +#define _IO_have_backup(fp) ((fp)->_IO_backup_base != NULL) +#define _IO_have_wbackup(fp) ((fp)->_wide_data->_IO_backup_base != NULL) #define _IO_in_backup(fp) ((fp)->_flags & _IO_IN_BACKUP) #define _IO_have_markers(fp) ((fp)->_markers != NULL) #define _IO_blen(fp) ((fp)->_IO_buf_end - (fp)->_IO_buf_base) |