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7b1d83da25
Softirq can interrupt ongoing packet from process context that is
walking over the percpu area that contains inner header offsets.
Disable bh and perform three checks before restoring the percpu inner
header offsets to validate that the percpu area is valid for this
skbuff:
1) If the NFT_PKTINFO_INNER_FULL flag is set on, then this skbuff
has already been parsed before for inner header fetching to
register.
2) Validate that the percpu area refers to this skbuff using the
skbuff pointer as a cookie. If there is a cookie mismatch, then
this skbuff needs to be parsed again.
3) Finally, validate if the percpu area refers to this tunnel type.
Only after these three checks the percpu area is restored to a on-stack
copy and bh is enabled again.
After inner header fetching, the on-stack copy is stored back to the
percpu area.
Fixes: 3a07327d10 ("netfilter: nft_inner: support for inner tunnel header matching")
Reported-by: syzbot+84d0441b9860f0d63285@syzkaller.appspotmail.com
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
Linux kernel
============
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be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.
In order to build the documentation, use ``make htmldocs`` or
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https://www.kernel.org/doc/html/latest/
There are various text files in the Documentation/ subdirectory,
several of them using the reStructuredText markup notation.
Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.