@kerneldude - any chance you could share your poc (perhaps email it to
[email protected] rather than post it publicly here)? I have tried
creating one via the following but I hit the CLI args limit before I can
get an xattr key long enough:
touch bar
tar --pax-option SCHILY.xattr.user.$(python3 -c "print('a'*131048)"):=test -cf
poc-crafted.tar bar
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https://bugs.launchpad.net/bugs/2029464
Title:
A stack overflow in GNU Tar
Status in tar package in Ubuntu:
New
Bug description:
A stack overflow vulnerability exists in GNU Tar up to including v1.34, as
far as I can see, Ubuntu is using v1.3.
The bug exists in the function xattr_decoder() in xheader.c, where alloca()
is used and it may overflow the stack if a sufficiently long xattr key is used.
The vulnerability can be triggered when extracting a tar/pax archive that
contains such a long xattr key.
Vulnerable code:
https://git.savannah.gnu.org/cgit/tar.git/tree/src/xheader.c?h=release_1_34#n1723
PoC tar archive is attached in a zip archive to reduce the size.
I reported the vulnerability yesterday to GNU Tar maintainers and they
replied that the issue was fixed in the version that was released two
weeks ago:
"Sergey fixed that bug here:
https://git.savannah.gnu.org/cgit/tar.git/commit/?id=a339f05cd269013fa133d2f148d73f6f7d4247e4
and the fix appears in tar 1.35, released July 18.
"
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