| Message ID | 1470254248-24041-1-git-send-email-bo.li.liu@oracle.com (mailing list archive) |
|---|---|
| State | Superseded |
| Headers | show |
On Wed, 03 Aug 2016 12:57:28 -0700, Liu Bo wrote: > When btree node (level = 1) has nritems which equals to zero, > we can end up with panic due to insert_ptr()'s > > BUG_ON(slot > nritems); > > where slot is 1 and nritems is 0, as copy_for_split() calls > insert_ptr(.., path->slots[1] + 1, ...); > > A invalid value results in the whole mess, this adds the check > for btree's node nritems so that we stop reading block when > when something is wrong. > > Signed-off-by: Liu Bo <bo.li.liu@oracle.com> > --- > fs/btrfs/disk-io.c | 17 +++++++++++++++++ > 1 file changed, 17 insertions(+) > > diff --git a/fs/btrfs/disk-io.c b/fs/btrfs/disk-io.c > index 37d1780..a5a22be 100644 > --- a/fs/btrfs/disk-io.c > +++ b/fs/btrfs/disk-io.c > @@ -612,6 +612,20 @@ static noinline int check_leaf(struct btrfs_root *root, > return 0; > } > > +static noinline int check_node(struct btrfs_root *root, > + struct extent_buffer *node) > +{ > + unsigned long nr = btrfs_header_nritems(node); > + > + if (nr <= 0 || nr >= BTRFS_NODEPTRS_PER_BLOCK(root)) { > + btrfs_crit(root->fs_info, > + "corrupt node: block %llu root %llu nritems %lu\n", I think the trailing \n can be dropped here, btrfs_crit() already provides a proper newline. -h -- To unsubscribe from this list: send the line "unsubscribe linux-btrfs" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
On 08/05/16 11:24, Holger Hoffstätte wrote: > On Wed, 03 Aug 2016 12:57:28 -0700, Liu Bo wrote: > >> When btree node (level = 1) has nritems which equals to zero, >> we can end up with panic due to insert_ptr()'s >> >> BUG_ON(slot > nritems); >> >> where slot is 1 and nritems is 0, as copy_for_split() calls >> insert_ptr(.., path->slots[1] + 1, ...); >> >> A invalid value results in the whole mess, this adds the check >> for btree's node nritems so that we stop reading block when >> when something is wrong. >> >> Signed-off-by: Liu Bo <bo.li.liu@oracle.com> >> --- >> fs/btrfs/disk-io.c | 17 +++++++++++++++++ >> 1 file changed, 17 insertions(+) >> >> diff --git a/fs/btrfs/disk-io.c b/fs/btrfs/disk-io.c >> index 37d1780..a5a22be 100644 >> --- a/fs/btrfs/disk-io.c >> +++ b/fs/btrfs/disk-io.c >> @@ -612,6 +612,20 @@ static noinline int check_leaf(struct btrfs_root *root, >> return 0; >> } >> >> +static noinline int check_node(struct btrfs_root *root, >> + struct extent_buffer *node) >> +{ >> + unsigned long nr = btrfs_header_nritems(node); >> + >> + if (nr <= 0 || nr >= BTRFS_NODEPTRS_PER_BLOCK(root)) { >> + btrfs_crit(root->fs_info, >> + "corrupt node: block %llu root %llu nritems %lu\n", > > I think the trailing \n can be dropped here, btrfs_crit() already provides > a proper newline. On top of that I get a whole bunch of false positives with this patch. Files that are perfectly readable without it now error out, in which case the logged nritems is always 493 - regardless of file or containing subvolume. Something is fishy here. -h -- To unsubscribe from this list: send the line "unsubscribe linux-btrfs" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
On Wed, Aug 03, 2016 at 12:57:28PM -0700, Liu Bo wrote: > When btree node (level = 1) has nritems which equals to zero, > we can end up with panic due to insert_ptr()'s > > BUG_ON(slot > nritems); > > where slot is 1 and nritems is 0, as copy_for_split() calls > insert_ptr(.., path->slots[1] + 1, ...); > > A invalid value results in the whole mess, this adds the check > for btree's node nritems so that we stop reading block when > when something is wrong. > > Signed-off-by: Liu Bo <bo.li.liu@oracle.com> > --- > fs/btrfs/disk-io.c | 17 +++++++++++++++++ > 1 file changed, 17 insertions(+) > > diff --git a/fs/btrfs/disk-io.c b/fs/btrfs/disk-io.c > index 37d1780..a5a22be 100644 > --- a/fs/btrfs/disk-io.c > +++ b/fs/btrfs/disk-io.c > @@ -612,6 +612,20 @@ static noinline int check_leaf(struct btrfs_root *root, > return 0; > } > > +static noinline int check_node(struct btrfs_root *root, > + struct extent_buffer *node) > +{ > + unsigned long nr = btrfs_header_nritems(node); > + > + if (nr <= 0 || nr >= BTRFS_NODEPTRS_PER_BLOCK(root)) { nr is unsigned, so it's just "== 0" and the BTRFS_NODEPTRS_PER_BLOCK value is inclusive, which should explain Holger's findings. 493 * sizeof (btrfs_key_ptr) + sizeof (btrfs_header) + slack = nodesize 493 * 33 + 101 + slack = 16k (the closest value) gives slack = 14 (smaller than sizeof (btrfs_key_ptr)) -- To unsubscribe from this list: send the line "unsubscribe linux-btrfs" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
On Tue, Aug 16, 2016 at 06:50:00PM +0200, David Sterba wrote: > On Wed, Aug 03, 2016 at 12:57:28PM -0700, Liu Bo wrote: > > When btree node (level = 1) has nritems which equals to zero, > > we can end up with panic due to insert_ptr()'s > > > > BUG_ON(slot > nritems); > > > > where slot is 1 and nritems is 0, as copy_for_split() calls > > insert_ptr(.., path->slots[1] + 1, ...); > > > > A invalid value results in the whole mess, this adds the check > > for btree's node nritems so that we stop reading block when > > when something is wrong. > > > > Signed-off-by: Liu Bo <bo.li.liu@oracle.com> > > --- > > fs/btrfs/disk-io.c | 17 +++++++++++++++++ > > 1 file changed, 17 insertions(+) > > > > diff --git a/fs/btrfs/disk-io.c b/fs/btrfs/disk-io.c > > index 37d1780..a5a22be 100644 > > --- a/fs/btrfs/disk-io.c > > +++ b/fs/btrfs/disk-io.c > > @@ -612,6 +612,20 @@ static noinline int check_leaf(struct btrfs_root *root, > > return 0; > > } > > > > +static noinline int check_node(struct btrfs_root *root, > > + struct extent_buffer *node) > > +{ > > + unsigned long nr = btrfs_header_nritems(node); > > + > > + if (nr <= 0 || nr >= BTRFS_NODEPTRS_PER_BLOCK(root)) { > > nr is unsigned, so it's just "== 0" > > and the BTRFS_NODEPTRS_PER_BLOCK value is inclusive, which should > explain Holger's findings. > > 493 * sizeof (btrfs_key_ptr) + sizeof (btrfs_header) + slack = nodesize > > 493 * 33 + 101 + slack = 16k (the closest value) > > gives slack = 14 (smaller than sizeof (btrfs_key_ptr)) Oh, right, I made a mistake when getting the assumption from insert_ptr(), it should be nr > BTRFS_NODEPTRS_PER_BLOCK(root). Thanks, -liubo -- To unsubscribe from this list: send the line "unsubscribe linux-btrfs" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
diff --git a/fs/btrfs/disk-io.c b/fs/btrfs/disk-io.c index 37d1780..a5a22be 100644 --- a/fs/btrfs/disk-io.c +++ b/fs/btrfs/disk-io.c @@ -612,6 +612,20 @@ static noinline int check_leaf(struct btrfs_root *root, return 0; } +static noinline int check_node(struct btrfs_root *root, + struct extent_buffer *node) +{ + unsigned long nr = btrfs_header_nritems(node); + + if (nr <= 0 || nr >= BTRFS_NODEPTRS_PER_BLOCK(root)) { + btrfs_crit(root->fs_info, + "corrupt node: block %llu root %llu nritems %lu\n", + node->start, root->objectid, nr); + return -EIO; + } + return 0; +} + static int btree_readpage_end_io_hook(struct btrfs_io_bio *io_bio, u64 phy_offset, struct page *page, u64 start, u64 end, int mirror) @@ -682,6 +696,9 @@ static int btree_readpage_end_io_hook(struct btrfs_io_bio *io_bio, ret = -EIO; } + if (found_level > 0 && check_node(root, eb)) + ret = -EIO; + if (!ret) set_extent_buffer_uptodate(eb); err:
When btree node (level = 1) has nritems which equals to zero, we can end up with panic due to insert_ptr()'s BUG_ON(slot > nritems); where slot is 1 and nritems is 0, as copy_for_split() calls insert_ptr(.., path->slots[1] + 1, ...); A invalid value results in the whole mess, this adds the check for btree's node nritems so that we stop reading block when when something is wrong. Signed-off-by: Liu Bo <bo.li.liu@oracle.com> --- fs/btrfs/disk-io.c | 17 +++++++++++++++++ 1 file changed, 17 insertions(+)