| Message ID | 5048C2F6.8090102@inktank.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
Reviewed-by: Yehuda Sadeh <yehuda@inktank.com> On Thu, Sep 6, 2012 at 8:36 AM, Alex Elder <elder@inktank.com> wrote: > The only thing the on-disk snap_names_len field is needed is to > size the buffer allocated to hold a copy of the snapshot names > for an rbd image. > > So don't bother saving it in the in-core rbd_image_header structure. > Just use a local variable to hold the required buffer size while > it's needed. > > Move the code that actually copies the snapshot names up closer > to where the required length is saved. > > Signed-off-by: Alex Elder <elder@inktank.com> > --- > v2: - Return -EIO rather than BUG_ON() as suggested by Yehuda. > - Added a comment explaining why a memcpy() will not exceed > the length of the on-disk buffer, in response to Yehuda's > concern. > > drivers/block/rbd.c | 26 +++++++++++++------------- > 1 file changed, 13 insertions(+), 13 deletions(-) > > Index: b/drivers/block/rbd.c > =================================================================== > --- a/drivers/block/rbd.c > +++ b/drivers/block/rbd.c > @@ -81,7 +81,6 @@ struct rbd_image_header { > __u8 crypt_type; > __u8 comp_type; > struct ceph_snap_context *snapc; > - u64 snap_names_len; > u32 total_snaps; > > char *snap_names; > @@ -534,12 +533,21 @@ static int rbd_header_from_disk(struct r > header->object_prefix[len] = '\0'; > > if (snap_count) { > - header->snap_names_len = le64_to_cpu(ondisk->snap_names_len); > - BUG_ON(header->snap_names_len > (u64) SIZE_MAX); > - header->snap_names = kmalloc(header->snap_names_len, > - GFP_KERNEL); > + u64 snap_names_len = le64_to_cpu(ondisk->snap_names_len); > + > + if (snap_names_len > (u64) SIZE_MAX) > + return -EIO; > + header->snap_names = kmalloc(snap_names_len, GFP_KERNEL); > if (!header->snap_names) > goto out_err; > + /* > + * Note that rbd_dev_v1_header_read() guarantees > + * the ondisk buffer we're working with has > + * snap_names_len bytes beyond the end of the > + * snapshot id array, this memcpy() is safe. > + */ > + memcpy(header->snap_names, &ondisk->snaps[snap_count], > + snap_names_len); > > size = snap_count * sizeof (*header->snap_sizes); > header->snap_sizes = kmalloc(size, GFP_KERNEL); > @@ -547,7 +555,6 @@ static int rbd_header_from_disk(struct r > goto out_err; > } else { > WARN_ON(ondisk->snap_names_len); > - header->snap_names_len = 0; > header->snap_names = NULL; > header->snap_sizes = NULL; > } > @@ -579,10 +586,6 @@ static int rbd_header_from_disk(struct r > header->snap_sizes[i] = > le64_to_cpu(ondisk->snaps[i].image_size); > } > - > - /* copy snapshot names */ > - memcpy(header->snap_names, &ondisk->snaps[snap_count], > - header->snap_names_len); > } > > return 0; > @@ -592,7 +595,6 @@ out_err: > header->snap_sizes = NULL; > kfree(header->snap_names); > header->snap_names = NULL; > - header->snap_names_len = 0; > kfree(header->object_prefix); > header->object_prefix = NULL; > > @@ -660,7 +662,6 @@ static void rbd_header_free(struct rbd_i > header->snap_sizes = NULL; > kfree(header->snap_names); > header->snap_names = NULL; > - header->snap_names_len = 0; > ceph_put_snap_context(header->snapc); > header->snapc = NULL; > } > @@ -1800,7 +1801,6 @@ static int __rbd_refresh_header(struct r > rbd_dev->header.total_snaps = h.total_snaps; > rbd_dev->header.snapc = h.snapc; > rbd_dev->header.snap_names = h.snap_names; > - rbd_dev->header.snap_names_len = h.snap_names_len; > rbd_dev->header.snap_sizes = h.snap_sizes; > /* Free the extra copy of the object prefix */ > WARN_ON(strcmp(rbd_dev->header.object_prefix, h.object_prefix)); > > -- > To unsubscribe from this list: send the line "unsubscribe ceph-devel" in > the body of a message to majordomo@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html -- To unsubscribe from this list: send the line "unsubscribe ceph-devel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
Index: b/drivers/block/rbd.c =================================================================== --- a/drivers/block/rbd.c +++ b/drivers/block/rbd.c @@ -81,7 +81,6 @@ struct rbd_image_header { __u8 crypt_type; __u8 comp_type; struct ceph_snap_context *snapc; - u64 snap_names_len; u32 total_snaps; char *snap_names; @@ -534,12 +533,21 @@ static int rbd_header_from_disk(struct r header->object_prefix[len] = '\0'; if (snap_count) { - header->snap_names_len = le64_to_cpu(ondisk->snap_names_len); - BUG_ON(header->snap_names_len > (u64) SIZE_MAX); - header->snap_names = kmalloc(header->snap_names_len, - GFP_KERNEL); + u64 snap_names_len = le64_to_cpu(ondisk->snap_names_len); + + if (snap_names_len > (u64) SIZE_MAX) + return -EIO; + header->snap_names = kmalloc(snap_names_len, GFP_KERNEL); if (!header->snap_names) goto out_err; + /* + * Note that rbd_dev_v1_header_read() guarantees + * the ondisk buffer we're working with has + * snap_names_len bytes beyond the end of the + * snapshot id array, this memcpy() is safe. + */ + memcpy(header->snap_names, &ondisk->snaps[snap_count], + snap_names_len); size = snap_count * sizeof (*header->snap_sizes); header->snap_sizes = kmalloc(size, GFP_KERNEL); @@ -547,7 +555,6 @@ static int rbd_header_from_disk(struct r goto out_err; } else { WARN_ON(ondisk->snap_names_len); - header->snap_names_len = 0; header->snap_names = NULL; header->snap_sizes = NULL; } @@ -579,10 +586,6 @@ static int rbd_header_from_disk(struct r header->snap_sizes[i] = le64_to_cpu(ondisk->snaps[i].image_size); } - - /* copy snapshot names */ - memcpy(header->snap_names, &ondisk->snaps[snap_count], - header->snap_names_len); } return 0; @@ -592,7 +595,6 @@ out_err: header->snap_sizes = NULL; kfree(header->snap_names); header->snap_names = NULL; - header->snap_names_len = 0; kfree(header->object_prefix); header->object_prefix = NULL; @@ -660,7 +662,6 @@ static void rbd_header_free(struct rbd_i header->snap_sizes = NULL; kfree(header->snap_names); header->snap_names = NULL; - header->snap_names_len = 0; ceph_put_snap_context(header->snapc); header->snapc = NULL; } @@ -1800,7 +1801,6 @@ static int __rbd_refresh_header(struct r rbd_dev->header.total_snaps = h.total_snaps; rbd_dev->header.snapc = h.snapc; rbd_dev->header.snap_names = h.snap_names; - rbd_dev->header.snap_names_len = h.snap_names_len; rbd_dev->header.snap_sizes = h.snap_sizes; /* Free the extra copy of the object prefix */ WARN_ON(strcmp(rbd_dev->header.object_prefix, h.object_prefix));
The only thing the on-disk snap_names_len field is needed is to size the buffer allocated to hold a copy of the snapshot names for an rbd image. So don't bother saving it in the in-core rbd_image_header structure. Just use a local variable to hold the required buffer size while it's needed. Move the code that actually copies the snapshot names up closer to where the required length is saved. Signed-off-by: Alex Elder <elder@inktank.com> --- v2: - Return -EIO rather than BUG_ON() as suggested by Yehuda. - Added a comment explaining why a memcpy() will not exceed the length of the on-disk buffer, in response to Yehuda's concern. drivers/block/rbd.c | 26 +++++++++++++------------- 1 file changed, 13 insertions(+), 13 deletions(-) -- To unsubscribe from this list: send the line "unsubscribe ceph-devel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html