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Chang S. Bae 00fcd8f33e x86/signal: Detect and prevent an alternate signal stack overflow
[ Upstream commit 2beb4a53fc3f1081cedc1c1a198c7f56cc4fc60c ]

The kernel pushes context on to the userspace stack to prepare for the
user's signal handler. When the user has supplied an alternate signal
stack, via sigaltstack(2), it is easy for the kernel to verify that the
stack size is sufficient for the current hardware context.

Check if writing the hardware context to the alternate stack will exceed
it's size. If yes, then instead of corrupting user-data and proceeding with
the original signal handler, an immediate SIGSEGV signal is delivered.

Refactor the stack pointer check code from on_sig_stack() and use the new
helper.

While the kernel allows new source code to discover and use a sufficient
alternate signal stack size, this check is still necessary to protect
binaries with insufficient alternate signal stack size from data
corruption.

Fixes: c2bc11f10a ("x86, AVX-512: Enable AVX-512 States Context Switch")
Reported-by: Florian Weimer <fweimer@redhat.com>
Suggested-by: Jann Horn <jannh@google.com>
Suggested-by: Andy Lutomirski <luto@kernel.org>
Signed-off-by: Chang S. Bae <chang.seok.bae@intel.com>
Signed-off-by: Borislav Petkov <bp@suse.de>
Reviewed-by: Len Brown <len.brown@intel.com>
Acked-by: Thomas Gleixner <tglx@linutronix.de>
Link: https://lkml.kernel.org/r/20210518200320.17239-6-chang.seok.bae@intel.com
Link: https://bugzilla.kernel.org/show_bug.cgi?id=153531
Signed-off-by: Sasha Levin <sashal@kernel.org>
2021-07-20 16:10:49 +02:00
arch x86/signal: Detect and prevent an alternate signal stack overflow 2021-07-20 16:10:49 +02:00
block
certs
crypto
Documentation
drivers virtio_console: Assure used length from device is limited 2021-07-20 16:10:49 +02:00
fs NFS: nfs_find_open_context() may only select open files 2021-07-20 16:10:48 +02:00
include x86/signal: Detect and prevent an alternate signal stack overflow 2021-07-20 16:10:49 +02:00
init
ipc
kernel srcu: Fix broken node geometry after early ssp init 2021-07-20 16:10:41 +02:00
lib lib/decompress_unlz4.c: correctly handle zero-padding around initrds. 2021-07-20 16:10:46 +02:00
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samples
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sound ALSA: usb-audio: scarlett2: Fix 6i6 Gen 2 line out descriptions 2021-07-20 16:10:46 +02:00
tools selftests/powerpc: Fix "no_handler" EBB selftest 2021-07-20 16:10:44 +02:00
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README

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.