kprobes, x86/ptrace.h: Make regs_get_kernel_stack_nth() not fault on bad stack
commit1f9d5f75a7cbb772aaee1b6b48a423a25edc01e6
authorSteven Rostedt (VMware) <rostedt@goodmis.org>
Wed, 17 Oct 2018 20:59:51 +0000 (17 16:59 -0400)
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>
Thu, 28 Nov 2019 17:25:44 +0000 (28 18:25 +0100)
tree760d9bc36f87eb71d489cc493508982233f43aaf
parentfd773539c25698e539b10f0bf712dd99798a6b7f
kprobes, x86/ptrace.h: Make regs_get_kernel_stack_nth() not fault on bad stack

[ Upstream commit c2712b858187f5bcd7b042fe4daa3ba3a12635c0 ]

Andy had some concerns about using regs_get_kernel_stack_nth() in a new
function regs_get_kernel_argument() as if there's any error in the stack
code, it could cause a bad memory access. To be on the safe side, call
probe_kernel_read() on the stack address to be extra careful in accessing
the memory. A helper function, regs_get_kernel_stack_nth_addr(), was added
to just return the stack address (or NULL if not on the stack), that will be
used to find the address (and could be used by other functions) and read the
address with kernel_probe_read().

Requested-by: Andy Lutomirski <luto@amacapital.net>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
Reviewed-by: Joel Fernandes (Google) <joel@joelfernandes.org>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/20181017165951.09119177@gandalf.local.home
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
arch/x86/include/asm/ptrace.h