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Filename Latest commit message Latest commit date
Michael Ellerman 38aa7f32df powerpc/64/tm: Don't let userspace set regs->trap via sigreturn
commit c7def7fbdeaa25feaa19caf4a27c5d10bd8789e4 upstream.

In restore_tm_sigcontexts() we take the trap value directly from the
user sigcontext with no checking:

	err |= __get_user(regs->trap, &sc->gp_regs[PT_TRAP]);

This means we can be in the kernel with an arbitrary regs->trap value.

Although that's not immediately problematic, there is a risk we could
trigger one of the uses of CHECK_FULL_REGS():

	#define CHECK_FULL_REGS(regs)	BUG_ON(regs->trap & 1)

It can also cause us to unnecessarily save non-volatile GPRs again in
save_nvgprs(), which shouldn't be problematic but is still wrong.

It's also possible it could trick the syscall restart machinery, which
relies on regs->trap not being == 0xc00 (see 9a81c16b52 ("powerpc:
fix double syscall restarts")), though I haven't been able to make
that happen.

Finally it doesn't match the behaviour of the non-TM case, in
restore_sigcontext() which zeroes regs->trap.

So change restore_tm_sigcontexts() to zero regs->trap.

This was discovered while testing Nick's upcoming rewrite of the
syscall entry path. In that series the call to save_nvgprs() prior to
signal handling (do_notify_resume()) is removed, which leaves the
low-bit of regs->trap uncleared which can then trigger the FULL_REGS()
WARNs in setup_tm_sigcontexts().

Fixes: 2b0a576d15 ("powerpc: Add new transactional memory state to the signal context")
Cc: stable@vger.kernel.org # v3.9+
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20200401023836.3286664-1-mpe@ellerman.id.au
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2020-04-17 10:50:22 +02:00
arch powerpc/64/tm: Don't let userspace set regs->trap via sigreturn 2020-04-17 10:50:22 +02:00
block block, bfq: fix use-after-free in bfq_idle_slice_timer_body 2020-04-17 10:50:05 +02:00
certs
crypto crypto: rng - Fix a refcounting bug in crypto_rng_reset() 2020-04-17 10:50:16 +02:00
Documentation ALSA: hda/realtek - Remove now-unnecessary XPS 13 headphone noise fixups 2020-04-17 10:50:08 +02:00
drivers xen/blkfront: fix memory allocation flags in blkfront_setup_indirect() 2020-04-17 10:50:22 +02:00
fs hfsplus: fix crash and filesystem corruption when deleting files 2020-04-17 10:50:22 +02:00
include xarray: Fix early termination of xas_for_each_marked 2020-04-17 10:50:18 +02:00
init kbuild: remove header compile test 2020-03-05 16:43:47 +01:00
ipc Revert "ipc,sem: remove uneeded sem_undo_list lock usage in exit_sem()" 2020-02-28 17:22:20 +01:00
kernel kmod: make request_module() return an error when autoloading is disabled 2020-04-17 10:50:22 +02:00
lib xarray: Fix early termination of xas_for_each_marked 2020-04-17 10:50:18 +02:00
LICENSES
mm mm, memcg: do not high throttle allocators based on wraparound 2020-04-17 10:50:17 +02:00
net cfg80211: Do not warn on same channel at the end of CSA 2020-04-17 10:49:59 +02:00
samples samples/bpf: Set -fno-stack-protector when building BPF programs 2020-02-24 08:36:36 +01:00
scripts kconfig: introduce m32-flag and m64-flag 2020-04-08 09:08:37 +02:00
security KEYS: reaching the keys quotas correctly 2020-04-17 10:50:11 +02:00
sound ALSA: hda/realtek - Add quirk for MSI GL63 2020-04-17 10:50:08 +02:00
tools perf tools: Support Python 3.8+ in Makefile 2020-04-17 10:50:21 +02:00
usr initramfs: restore default compression behavior 2020-04-08 09:08:38 +02:00
virt KVM: Check for a bad hva before dropping into the ghc slow path 2020-03-05 16:43:48 +01:00
.clang-format
.cocciconfig
.get_maintainer.ignore
.gitattributes
.gitignore
.mailmap
COPYING
CREDITS
Kbuild
Kconfig
MAINTAINERS MAINTAINERS: Update drm/i915 bug filing URL 2020-02-28 17:22:19 +01:00
Makefile Linux 5.4.32 2020-04-13 10:48:18 +02:00
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.