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Commit 02ad5d8d authored by Richard Weinberger's avatar Richard Weinberger Committed by Greg Kroah-Hartman
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um: Fix PTRACE_POKEUSER on x86_64 



commit 9abc74a22d85ab29cef9896a2582a530da7e79bf upstream.

This is broken since ever but sadly nobody noticed.
Recent versions of GDB set DR_CONTROL unconditionally and
UML dies due to a heap corruption. It turns out that
the PTRACE_POKEUSER was copy&pasted from i386 and assumes
that addresses are 4 bytes long.

Fix that by using 8 as address size in the calculation.

Reported-by: default avatarjie cao <cj3054@gmail.com>
Signed-off-by: default avatarRichard Weinberger <richard@nod.at>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent 3e576d76

arch/x86/um/ptrace_64.c

+1 −1
Original line number Diff line number Diff line
@@ -120,7 +120,7 @@ int poke_user(struct task_struct *child, long addr, long data) 
	else if ((addr >= offsetof(struct user, u_debugreg[0])) &&

		(addr <= offsetof(struct user, u_debugreg[7]))) {

		addr -= offsetof(struct user, u_debugreg[0]);

		addr = addr >> 2;

		addr = addr >> 3;

		if ((addr == 4) || (addr == 5))

			return -EIO;

		child->thread.arch.debugregs[addr] = data;