| Message ID | 20190831020432.61473-1-liq3ea@163.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | block: qcow2: free 'refcount_table' in error path | expand |
Am 31.08.2019 um 04:04 hat Li Qiang geschrieben: > Currently, when doing './check -qcow2 098'. We can get following > asan output: > > qemu-img: Could not empty blkdebug:TEST_DIR/blkdebug.conf:TEST_DIR/t.IMGFMT: Input/output error > + > +================================================================= > +==60365==ERROR: LeakSanitizer: detected memory leaks > + > +Direct leak of 65536 byte(s) in 1 object(s) allocated from: > + #0 0x7f3ed729fd38 in __interceptor_calloc (/usr/lib/x86_64-linux-gnu/libasan.so.4+0xded38) > + #1 0x56274517fe66 in make_completely_empty block/IMGFMT.c:4219 > + #2 0x562745180e51 in IMGFMT_make_empty block/IMGFMT.c:4313 > + #3 0x56274509b14e in img_commit /home/test/qemu5/qemu/qemu-img.c:1053 > + #4 0x5627450b4b74 in main /home/test/qemu5/qemu/qemu-img.c:5097 > + #5 0x7f3ed4f2fb96 in __libc_start_main (/lib/x86_64-linux-gnu/libc.so.6+0x21b96) > > This is because the logic of clean resource in 'make_completely_empty' is > wrong. The patch frees the 's->refcount_table' in error path. > > Signed-off-by: Li Qiang <liq3ea@163.com> This is wrong. You can never free s->refcount_table and leave it as a dangling pointer. It is state that is only supposed to be freed in qcow2_close() -> qcow2_refcount_close(). The only reason why it doesn't crash with your change is that you also make the error fatal (bs->drv = NULL) so that any further I/O on the image will fail anyway. But there is no good reason to make these errors fatal. Kevin > block/qcow2.c | 9 +++++---- > 1 file changed, 5 insertions(+), 4 deletions(-) > > diff --git a/block/qcow2.c b/block/qcow2.c > index 7c5a4859f7..23fe713d4c 100644 > --- a/block/qcow2.c > +++ b/block/qcow2.c > @@ -4243,7 +4243,7 @@ static int make_completely_empty(BlockDriverState *bs) > ret = bdrv_pwrite_sync(bs->file, s->cluster_size, > &rt_entry, sizeof(rt_entry)); > if (ret < 0) { > - goto fail_broken_refcounts; > + goto fail; > } > s->refcount_table[0] = 2 * s->cluster_size; > > @@ -4252,7 +4252,7 @@ static int make_completely_empty(BlockDriverState *bs) > offset = qcow2_alloc_clusters(bs, 3 * s->cluster_size + l1_size2); > if (offset < 0) { > ret = offset; > - goto fail_broken_refcounts; > + goto fail; > } else if (offset > 0) { > error_report("First cluster in emptied image is in use"); > abort(); > @@ -4274,6 +4274,9 @@ static int make_completely_empty(BlockDriverState *bs) > > return 0; > > +fail: > + g_free(s->refcount_table); > + > fail_broken_refcounts: > /* The BDS is unusable at this point. If we wanted to make it usable, we > * would have to call qcow2_refcount_close(), qcow2_refcount_init(), > @@ -4283,8 +4286,6 @@ fail_broken_refcounts: > * that that sequence will fail as well. Therefore, just eject the BDS. */ > bs->drv = NULL; > > -fail: > - g_free(new_reftable); > return ret; > } > > -- > 2.17.1 > >
diff --git a/block/qcow2.c b/block/qcow2.c index 7c5a4859f7..23fe713d4c 100644 --- a/block/qcow2.c +++ b/block/qcow2.c @@ -4243,7 +4243,7 @@ static int make_completely_empty(BlockDriverState *bs) ret = bdrv_pwrite_sync(bs->file, s->cluster_size, &rt_entry, sizeof(rt_entry)); if (ret < 0) { - goto fail_broken_refcounts; + goto fail; } s->refcount_table[0] = 2 * s->cluster_size; @@ -4252,7 +4252,7 @@ static int make_completely_empty(BlockDriverState *bs) offset = qcow2_alloc_clusters(bs, 3 * s->cluster_size + l1_size2); if (offset < 0) { ret = offset; - goto fail_broken_refcounts; + goto fail; } else if (offset > 0) { error_report("First cluster in emptied image is in use"); abort(); @@ -4274,6 +4274,9 @@ static int make_completely_empty(BlockDriverState *bs) return 0; +fail: + g_free(s->refcount_table); + fail_broken_refcounts: /* The BDS is unusable at this point. If we wanted to make it usable, we * would have to call qcow2_refcount_close(), qcow2_refcount_init(), @@ -4283,8 +4286,6 @@ fail_broken_refcounts: * that that sequence will fail as well. Therefore, just eject the BDS. */ bs->drv = NULL; -fail: - g_free(new_reftable); return ret; }
Currently, when doing './check -qcow2 098'. We can get following asan output: qemu-img: Could not empty blkdebug:TEST_DIR/blkdebug.conf:TEST_DIR/t.IMGFMT: Input/output error + +================================================================= +==60365==ERROR: LeakSanitizer: detected memory leaks + +Direct leak of 65536 byte(s) in 1 object(s) allocated from: + #0 0x7f3ed729fd38 in __interceptor_calloc (/usr/lib/x86_64-linux-gnu/libasan.so.4+0xded38) + #1 0x56274517fe66 in make_completely_empty block/IMGFMT.c:4219 + #2 0x562745180e51 in IMGFMT_make_empty block/IMGFMT.c:4313 + #3 0x56274509b14e in img_commit /home/test/qemu5/qemu/qemu-img.c:1053 + #4 0x5627450b4b74 in main /home/test/qemu5/qemu/qemu-img.c:5097 + #5 0x7f3ed4f2fb96 in __libc_start_main (/lib/x86_64-linux-gnu/libc.so.6+0x21b96) This is because the logic of clean resource in 'make_completely_empty' is wrong. The patch frees the 's->refcount_table' in error path. Signed-off-by: Li Qiang <liq3ea@163.com> --- block/qcow2.c | 9 +++++---- 1 file changed, 5 insertions(+), 4 deletions(-)