Dmitry V. Levin
b7dc5a071d
Commit 910cd32e552e ("parisc: Fix and enable seccomp filter support")
introduced a regression in ptrace-based syscall tampering: when tracer
changes syscall number to -1, the kernel fails to initialize %r28 with
-ENOSYS and subsequently fails to return the error code of the failed
syscall to userspace.
This erroneous behaviour could be observed with a simple strace syscall
fault injection command which is expected to print something like this:
$ strace -a0 -ewrite -einject=write:error=enospc echo hello
write(1, "hello\n", 6) = -1 ENOSPC (No space left on device) (INJECTED)
write(2, "echo: ", 6) = -1 ENOSPC (No space left on device) (INJECTED)
write(2, "write error", 11) = -1 ENOSPC (No space left on device) (INJECTED)
write(2, "\n", 1) = -1 ENOSPC (No space left on device) (INJECTED)
+++ exited with 1 +++
After commit 910cd32e552ea09caa89cdbe328e468979b030dd it loops printing
something like this instead:
write(1, "hello\n", 6../strace: Failed to tamper with process 12345: unexpectedly got no error (return value 0, error 0)
) = 0 (INJECTED)
This bug was found by strace test suite.
Fixes: 910cd32e552e ("parisc: Fix and enable seccomp filter support")
Cc: stable@vger.kernel.org # v4.5+
Signed-off-by: Dmitry V. Levin <ldv@altlinux.org>
Tested-by: Helge Deller <deller@gmx.de>
Signed-off-by: Helge Deller <deller@gmx.de>
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.