m68k: Fix stack mangling logics in sigreturn

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a) we should hold modifying regs->format until we know we *will* be
doing stack expansion; otherwise attacker can modify sigframe to
have wrong ->sc_formatvec and install SIGSEGV handler.

b) we should *not* mix copying saved extra stuff from userland with
expanding the stack; once we'd done that manual memmove, we'd better
not return to C, so cleanup is very hard to do.  The easiest way
is to copy it on stack first, making sure we won't overwrite on stack
expansion.  Fortunately that's easy to do...

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Geert Uytterhoeven <geert@linux-m68k.org>

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Al Viro 2010-10-06 14:09:43 -04:00 • committed by Geert Uytterhoeven

parent 90731d7537

commit ea52b58ccb

1 changed files with 61 additions and 112 deletions

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arch/m68k/kernel/signal.c

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