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author | Adhemerval Zanella <adhemerval.zanella@linaro.org> | 2017-11-22 18:33:15 -0200 |
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committer | Adhemerval Zanella <adhemerval.zanella@linaro.org> | 2017-12-12 17:29:54 -0200 |
commit | cc683f7ed4a5bd8ce2c9b715581de727b04eb599 (patch) | |
tree | cfd96d62028f35e6477284320fcdb16ce5e061b9 /libio/wfileops.c | |
parent | c80acdc3254cd4801c7605cf468ec137d9ee2d83 (diff) | |
download | glibc-cc683f7ed4a5bd8ce2c9b715581de727b04eb599.tar.gz glibc-cc683f7ed4a5bd8ce2c9b715581de727b04eb599.tar.xz glibc-cc683f7ed4a5bd8ce2c9b715581de727b04eb599.zip |
libio: Free backup area when it not required (BZ#22415)
Some libio operations fail to correctly free the backup area (created by _IO_{w}default_pbackfail on unget{w}c) resulting in either invalid buffer free operations or memory leaks. For instance, on the example provided by BZ#22415 a following fputc after a fseek to rewind the stream issues an invalid free on the buffer. It is because although _IO_file_overflow correctly (from fputc) correctly calls _IO_free_backup_area, the _IO_new_file_seekoff (called by fseek) updates the FILE internal pointers without first free the backup area (resulting in invalid values in the internal pointers). The wide version also shows an issue, but instead of accessing invalid pointers it leaks the backup memory on fseek/fputwc operation. Checked on x86_64-linux-gnu and i686-linux-gnu. * libio/Makefile (tests): Add tst-bz22415. (tst-bz22415-ENV): New rule. (generated): Add tst-bz22415.mtrace and tst-bz22415.check. (tests-special): Add tst-bz22415-mem.out. ($(objpfx)tst-bz22415-mem.out): New rule. * libio/fileops.c (_IO_new_file_seekoff): Call _IO_free_backup_area in case of a successful seek operation. * libio/wfileops.c (_IO_wfile_seekoff): Likewise. (_IO_wfile_overflow): Call _IO_free_wbackup_area in case a write buffer is required. * libio/tst-bz22415.c: New test.
Diffstat (limited to 'libio/wfileops.c')
-rw-r--r-- | libio/wfileops.c | 4 |
1 files changed, 4 insertions, 0 deletions
diff --git a/libio/wfileops.c b/libio/wfileops.c index 8756b6fe1a..91139e1375 100644 --- a/libio/wfileops.c +++ b/libio/wfileops.c @@ -421,6 +421,7 @@ _IO_wfile_overflow (_IO_FILE *f, wint_t wch) if (f->_wide_data->_IO_write_base == 0) { _IO_wdoallocbuf (f); + _IO_free_wbackup_area (f); _IO_wsetg (f, f->_wide_data->_IO_buf_base, f->_wide_data->_IO_buf_base, f->_wide_data->_IO_buf_base); @@ -850,6 +851,9 @@ _IO_wfile_seekoff (_IO_FILE *fp, _IO_off64_t offset, int dir, int mode) goto dumb; } } + + _IO_free_wbackup_area (fp); + /* At this point, dir==_IO_seek_set. */ /* If destination is within current buffer, optimize: */ |