mirror of
https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git
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Zhengchuan Liang
6c7fbdb8ff
[ Upstream commit9ca562bb8e] `ip6fl_seq_show()` walks the global flowlabel hash under the seq-file RCU read-side lock and prints `fl->opt->opt_nflen` when an option block is present. Exclusive flowlabels currently free `fl->opt` as soon as `fl->users` drops to zero in `fl_release()`. However, the surrounding `struct ip6_flowlabel` remains visible in the global hash table until later garbage collection removes it and `fl_free_rcu()` finally tears it down. A concurrent `/proc/net/ip6_flowlabel` reader can therefore race that early `kfree()` and dereference freed option state, triggering a crash in `ip6fl_seq_show()`. Fix this by keeping `fl->opt` alive until `fl_free_rcu()`. That matches the lifetime already required for the enclosing flowlabel while readers can still reach it under RCU. Fixes:d3aedd5ebd("ipv6 flowlabel: Convert hash list to RCU.") Reported-by: Yifan Wu <yifanwucs@gmail.com> Reported-by: Juefei Pu <tomapufckgml@gmail.com> Co-developed-by: Yuan Tan <yuantan098@gmail.com> Signed-off-by: Yuan Tan <yuantan098@gmail.com> Suggested-by: Xin Liu <bird@lzu.edu.cn> Tested-by: Ren Wei <enjou1224z@gmail.com> Signed-off-by: Zhengchuan Liang <zcliangcn@gmail.com> Signed-off-by: Ren Wei <n05ec@lzu.edu.cn> Reviewed-by: Eric Dumazet <edumazet@google.com> Link: https://patch.msgid.link/07351f0ec47bcee289576f39f9354f4a64add6e4.1774855883.git.zcliangcn@gmail.com Signed-off-by: Jakub Kicinski <kuba@kernel.org> Signed-off-by: Sasha Levin <sashal@kernel.org>
Linux kernel
============
There are several guides for kernel developers and users. These guides can
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
``make pdfdocs``. The formatted documentation can also be read online at:
https://www.kernel.org/doc/html/latest/
There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text 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.