| Message ID | 20231201000126.335263-1-briannorris@chromium.org |
|---|---|
| State | New |
| Headers | show |
| Series | lib/ext2fs: Validity checks for ext2fs_inode_scan_goto_blockgroup() | expand |
On Thu, Nov 30, 2023 at 04:01:18PM -0800, Brian Norris wrote: > We don't validate the 'group' argument, so it's easy to get underflows > or crashes here. > > This resolves issues seen in ureadahead, when it uses an old packfile > (with mismatching group indices) with a new filesystem. Say what now? The boot time pre-caching thing Ubuntu used to have? https://manpages.ubuntu.com/manpages/trusty/man8/ureadahead.8.html --D > Signed-off-by: Brian Norris <briannorris@chromium.org> > --- > > lib/ext2fs/inode.c | 3 +++ > 1 file changed, 3 insertions(+) > > diff --git a/lib/ext2fs/inode.c b/lib/ext2fs/inode.c > index 957d5aa9f9d6..96d854b5fb69 100644 > --- a/lib/ext2fs/inode.c > +++ b/lib/ext2fs/inode.c > @@ -313,6 +313,9 @@ static errcode_t get_next_blockgroup(ext2_inode_scan scan) > errcode_t ext2fs_inode_scan_goto_blockgroup(ext2_inode_scan scan, > int group) > { > + if (group <= 0 || group >= scan->fs->group_desc_count) > + return EXT2_ET_INVALID_ARGUMENT; > + > scan->current_group = group - 1; > scan->groups_left = scan->fs->group_desc_count - group; > scan->bad_block_ptr = 0; > -- > 2.43.0.rc2.451.g8631bc7472-goog > >
On Fri, Dec 1, 2023 at 8:24 AM Darrick J. Wong <djwong@kernel.org> wrote: > On Thu, Nov 30, 2023 at 04:01:18PM -0800, Brian Norris wrote: > > This resolves issues seen in ureadahead, when it uses an old packfile > > (with mismatching group indices) with a new filesystem. > > Say what now? The boot time pre-caching thing Ubuntu used to have? > https://manpages.ubuntu.com/manpages/trusty/man8/ureadahead.8.html Sure. ChromeOS still uses it. Steven Rostedt even bothered to do a talk about it recently: https://eoss2023.sched.com/event/1LcMw/the-resurrection-of-ureadahead-and-speeding-up-the-boot-process-and-preloading-applications-steven-rostedt-google Brian
On Fri, Dec 01, 2023 at 09:30:38AM -0800, Brian Norris wrote: > On Fri, Dec 1, 2023 at 8:24 AM Darrick J. Wong <djwong@kernel.org> wrote: > > On Thu, Nov 30, 2023 at 04:01:18PM -0800, Brian Norris wrote: > > > This resolves issues seen in ureadahead, when it uses an old packfile > > > (with mismatching group indices) with a new filesystem. > > > > Say what now? The boot time pre-caching thing Ubuntu used to have? > > https://manpages.ubuntu.com/manpages/trusty/man8/ureadahead.8.html > > Sure. ChromeOS still uses it. Steven Rostedt even bothered to do a > talk about it recently: > https://eoss2023.sched.com/event/1LcMw/the-resurrection-of-ureadahead-and-speeding-up-the-boot-process-and-preloading-applications-steven-rostedt-google Wow. I had no idea that ureadahead reads the inode blocks of a mounted ext* filesystem into the page cache. Welp, it's a good thing those are part of the static layout. Anyway, this fix looks correct to me, so I don't see any reason to hold this up... Reviewed-by: Darrick J. Wong <djwong@kernel.org> --D > > Brian >
diff --git a/lib/ext2fs/inode.c b/lib/ext2fs/inode.c index 957d5aa9f9d6..96d854b5fb69 100644 --- a/lib/ext2fs/inode.c +++ b/lib/ext2fs/inode.c @@ -313,6 +313,9 @@ static errcode_t get_next_blockgroup(ext2_inode_scan scan) errcode_t ext2fs_inode_scan_goto_blockgroup(ext2_inode_scan scan, int group) { + if (group <= 0 || group >= scan->fs->group_desc_count) + return EXT2_ET_INVALID_ARGUMENT; + scan->current_group = group - 1; scan->groups_left = scan->fs->group_desc_count - group; scan->bad_block_ptr = 0;
We don't validate the 'group' argument, so it's easy to get underflows or crashes here. This resolves issues seen in ureadahead, when it uses an old packfile (with mismatching group indices) with a new filesystem. Signed-off-by: Brian Norris <briannorris@chromium.org> --- lib/ext2fs/inode.c | 3 +++ 1 file changed, 3 insertions(+)