Herbert Xu ecabe8cd45 hwrng: core - Fix page fault dead lock on mmap-ed hwrng
commit 78aafb3884 upstream.

There is a dead-lock in the hwrng device read path.  This triggers
when the user reads from /dev/hwrng into memory also mmap-ed from
/dev/hwrng.  The resulting page fault triggers a recursive read
which then dead-locks.

Fix this by using a stack buffer when calling copy_to_user.

Reported-by: Edward Adam Davis <eadavis@qq.com>
Reported-by: syzbot+c52ab18308964d248092@syzkaller.appspotmail.com
Fixes: 9996508b33 ("hwrng: core - Replace u32 in driver API with byte array")
Cc: <stable@vger.kernel.org>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2024-01-31 16:18:50 -08:00
2024-01-31 16:18:49 -08:00
2024-01-31 16:18:49 -08:00
2024-01-25 15:35:41 -08:00
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2024-01-25 15:36:01 -08:00
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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.
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