linux-kernel - [PATCH RFC v2 3/4] mm: Support MAP_BELOW_HINT in vm_unmapped

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

Message-Id: <20240829-patches-below_hint_mmap-v2-3-638a28d9eae0@rivosinc.com>
Date: Thu, 29 Aug 2024 00:16:00 -0700
From: Charlie Jenkins <charlie@...osinc.com>
To: Arnd Bergmann <arnd@...db.de>, 
 Richard Henderson <richard.henderson@...aro.org>, 
 Ivan Kokshaysky <ink@...assic.park.msu.ru>, 
 Matt Turner <mattst88@...il.com>, Vineet Gupta <vgupta@...nel.org>, 
 Russell King <linux@...linux.org.uk>, Guo Ren <guoren@...nel.org>, 
 Huacai Chen <chenhuacai@...nel.org>, WANG Xuerui <kernel@...0n.name>, 
 Thomas Bogendoerfer <tsbogend@...ha.franken.de>, 
 "James E.J. Bottomley" <James.Bottomley@...senPartnership.com>, 
 Helge Deller <deller@....de>, Michael Ellerman <mpe@...erman.id.au>, 
 Nicholas Piggin <npiggin@...il.com>, 
 Christophe Leroy <christophe.leroy@...roup.eu>, 
 Naveen N Rao <naveen@...nel.org>, 
 Alexander Gordeev <agordeev@...ux.ibm.com>, 
 Gerald Schaefer <gerald.schaefer@...ux.ibm.com>, 
 Heiko Carstens <hca@...ux.ibm.com>, Vasily Gorbik <gor@...ux.ibm.com>, 
 Christian Borntraeger <borntraeger@...ux.ibm.com>, 
 Sven Schnelle <svens@...ux.ibm.com>, 
 Yoshinori Sato <ysato@...rs.sourceforge.jp>, Rich Felker <dalias@...c.org>, 
 John Paul Adrian Glaubitz <glaubitz@...sik.fu-berlin.de>, 
 "David S. Miller" <davem@...emloft.net>, 
 Andreas Larsson <andreas@...sler.com>, Thomas Gleixner <tglx@...utronix.de>, 
 Ingo Molnar <mingo@...hat.com>, Borislav Petkov <bp@...en8.de>, 
 Dave Hansen <dave.hansen@...ux.intel.com>, x86@...nel.org, 
 "H. Peter Anvin" <hpa@...or.com>, Andy Lutomirski <luto@...nel.org>, 
 Peter Zijlstra <peterz@...radead.org>, Muchun Song <muchun.song@...ux.dev>, 
 Andrew Morton <akpm@...ux-foundation.org>, 
 "Liam R. Howlett" <Liam.Howlett@...cle.com>, 
 Vlastimil Babka <vbabka@...e.cz>, 
 Lorenzo Stoakes <lorenzo.stoakes@...cle.com>, Shuah Khan <shuah@...nel.org>
Cc: linux-arch@...r.kernel.org, linux-kernel@...r.kernel.org, 
 linux-alpha@...r.kernel.org, linux-snps-arc@...ts.infradead.org, 
 linux-arm-kernel@...ts.infradead.org, linux-csky@...r.kernel.org, 
 loongarch@...ts.linux.dev, linux-mips@...r.kernel.org, 
 linux-parisc@...r.kernel.org, linuxppc-dev@...ts.ozlabs.org, 
 linux-s390@...r.kernel.org, linux-sh@...r.kernel.org, 
 sparclinux@...r.kernel.org, linux-mm@...ck.org, 
 linux-kselftest@...r.kernel.org, Charlie Jenkins <charlie@...osinc.com>
Subject: [PATCH RFC v2 3/4] mm: Support MAP_BELOW_HINT in
 vm_unmapped_area()

To ensure that all memory allocations comply with the new MAP_BELOW_HINT
flag, set the high_limit in vm_unmapped_area() to the hint address +
length at most. All callers to this function set the high_limit to
something reasonable, usually with space for a random offset and a gap
for the stack. To respect the provided high_limit, take the minimum of
hint+length and the given high_limit.

Signed-off-by: Charlie Jenkins <charlie@...osinc.com>
---
 mm/mmap.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/mm/mmap.c b/mm/mmap.c
index 34ba0db23678..459ad380c673 100644
--- a/mm/mmap.c
+++ b/mm/mmap.c
@@ -1766,6 +1766,9 @@ unsigned long vm_unmapped_area(struct vm_unmapped_area_info *info)
 {
 	unsigned long addr;

+	if (info->hint != 0 && info->mmap_flags & MAP_BELOW_HINT)
+		info->high_limit = MIN(info->high_limit, info->hint + info->length);
+
 	if (info->flags & VM_UNMAPPED_AREA_TOPDOWN)
 		addr = unmapped_area_topdown(info);
 	else

-- 
2.45.0