linux-kernel - [PATCH] shmat() and CONFIG_STACK

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [day] [month] [year] [list]

Message-Id: <200701112212.34000.deller@gmx.de>
Date:	Thu, 11 Jan 2007 22:12:33 +0100
From:	Helge Deller <deller@....de>
To:	Kernel Mailing List <linux-kernel@...r.kernel.org>
Subject: [PATCH] shmat() and CONFIG_STACK_GROWSUP

On PARISC-Linux the stack grows up, which is why on this platform CONFIG_STACK_GROWSUP is #defined by default.
The patch below allows shmat() to map the requested memory region on this platform directly below the start of the stack, without the need to reserve memory for a downward-growing stack.
Basically it gains a small region of 4 Pages in which shmat() may map memory on this platform.

Helge

diff --git a/ipc/shm.c b/ipc/shm.c
index 6d16bb6..f5cc635 100644
--- a/ipc/shm.c
+++ b/ipc/shm.c
@@ -852,6 +852,7 @@ long do_shmat(int shmid, char __user *sh
 		user_addr = ERR_PTR(-EINVAL);
 		if (find_vma_intersection(current->mm, addr, addr + size))
 			goto invalid;
+#ifndef CONFIG_STACK_GROWSUP
 		/*
 		 * If shm segment goes below stack, make sure there is some
 		 * space left for the stack to grow (at least 4 pages).
@@ -859,6 +860,7 @@ long do_shmat(int shmid, char __user *sh
 		if (addr < current->mm->start_stack &&
 		    addr > current->mm->start_stack - size - PAGE_SIZE * 5)
 			goto invalid;
+#endif
 	}
 		
 	user_addr = (void*) do_mmap (file, addr, size, prot, flags, 0);
-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/