fix(dracut-install): protect against broken links pointing to themselves #2478
Conversation
This file contains bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
`readlink` does not return an error if a symbolic link points to itself, which
can cause a stack overflow due to infinite recursion in the `get_real_file`
function.
Although this type of recursive links should not exist, we discovered this
issue on a real system. It can be reproduced as follows:
```
> ls -l /lib64/libblkid.so
-rwxr-xr-x 1 root root 224368 Aug 9 15:13 /lib64/libblkid.so
> rm -f /lib64/libblkid.so
> ln -s /lib64/libblkid.so /lib64/libblkid.so
> ls -l /lib64/libblkid.so
lrwxrwxrwx 1 root root 18 Aug 9 15:06 /lib64/libblkid.so -> /lib64/libblkid.so
> dracut -f -I "/lib64/libblkid.so" test.img
...
dracut-install: Handle '/lib64/libblkid.so'
dracut-install: dracut_install('/lib64/libblkid.so', '/lib64/libblkid.so', 0, 0, 1)
dracut-install: get_real_file('/lib64/libblkid.so')
dracut-install: get_real_file: readlink('/lib64/libblkid.so') returns '/lib64/libblkid.so'
dracut-install: get_real_file('/lib64/libblkid.so') => '/lib64/libblkid.so'
...
[infinite recursion]
...
dracut-install: dracut_install('/lib64/libblkid.so', '/lib64/libblkid.so', 0, 0, 1)
dracut-install: get_real_file('/lib64/libblkid.so')
dracut-install: get_real_file: readlink('/lib64/libblkid.so') returns '/lib64/libblkid.so'
dracut-install: get_real_file('/lib64/libblkid.so') => '/lib64/libblkid.so'
dracut-install: dracut_install('/lib64/libblkid.so', '/lib64/libblkid.so', 0, 0, 1)
/usr/lib/dracut/dracut-init.sh: line 298: 20949 Segmentation fault (core dumped) $DRACUT_INSTALL ${dracutsysrootdir:+-r "$dracutsysrootdir"} ${initdir:+-D "$initdir"} -a ${loginstall:+-L "$loginstall"} ${DRACUT_RESOLVE_DEPS:+-l} ${DRACUT_FIPS_MODE:+-f} ${_hostonly_install:+-H} "$@"
dracut: FAILED: /usr/lib/dracut/dracut-install --debug -D /var/tmp/dracut.dqLmOS/initramfs -a /lib64/libblkid.so
...
```
After applying this patch:
```
> dracut -f -I "/lib64/libblkid.so" test.img
...
dracut-install: Handle '/lib64/libblkid.so'
dracut-install: dracut_install('/lib64/libblkid.so', '/lib64/libblkid.so', 0, 0, 1)
dracut-install: get_real_file('/lib64/libblkid.so')
dracut-install: get_real_file: readlink('/lib64/libblkid.so') returns '/lib64/libblkid.so'
dracut-install: ERROR: '/lib64/libblkid.so' is pointing to itself.
dracut-install: ERROR: installing '/lib64/libblkid.so'
dracut: FAILED: /usr/lib/dracut/dracut-install --debug -D /var/tmp/dracut.4w8FVL/initramfs -a /lib64/libblkid.so
...
```
Sign up for free
to join this conversation on GitHub.
Already have an account?
Sign in to comment
Add this suggestion to a batch that can be applied as a single commit.
This suggestion is invalid because no changes were made to the code.
Suggestions cannot be applied while the pull request is closed.
Suggestions cannot be applied while viewing a subset of changes.
Only one suggestion per line can be applied in a batch.
Add this suggestion to a batch that can be applied as a single commit.
Applying suggestions on deleted lines is not supported.
You must change the existing code in this line in order to create a valid suggestion.
Outdated suggestions cannot be applied.
This suggestion has been applied or marked resolved.
Suggestions cannot be applied from pending reviews.
Suggestions cannot be applied on multi-line comments.
Suggestions cannot be applied while the pull request is queued to merge.
Suggestion cannot be applied right now. Please check back later.
readlinkdoes not return an error if a symbolic link points to itself, which can cause a stack overflow due to infinite recursion in theget_real_filefunction.Although this type of recursive links should not exist, we discovered this issue on a real system. It can be reproduced as follows:
After applying this patch:
Checklist