From: Dmitry Safonov <dsafonov@virtuozzo.com> To: <linux-kernel@vger.kernel.org> Cc: <0x7f454c46@gmail.com>, Dmitry Safonov <dsafonov@virtuozzo.com>, "Thomas Gleixner" <tglx@linutronix.de>, Ingo Molnar <mingo@redhat.com>, "H. Peter Anvin" <hpa@zytor.com>, Andy Lutomirski <luto@kernel.org>, Borislav Petkov <bp@suse.de>, <x86@kernel.org>, <linux-mm@kvack.org> Subject: [PATCHv4 4/5] x86/mm: check in_compat_syscall() instead TIF_ADDR32 for mmap(MAP_32BIT) Date: Mon, 30 Jan 2017 15:04:31 +0300 [thread overview] Message-ID: <20170130120432.6716-5-dsafonov@virtuozzo.com> (raw) In-Reply-To: <20170130120432.6716-1-dsafonov@virtuozzo.com> At this momet, logic in arch_get_unmapped_area{,_topdown} for mmaps with MAP_32BIT flag checks TIF_ADDR32 which means: o if 32-bit ELF changes mode to 64-bit on x86_64 and then tries to mmap() with MAP_32BIT it'll result in addr over 4Gb (as default is top-down allocation) o if 64-bit ELF changes mode to 32-bit and tries mmap() with MAP_32BIT, it'll allocate only memory in 1GB space: [0x40000000, 0x80000000). Fix it by handeling MAP_32BIT in 64-bit syscalls only. As a little bonus it'll make thread flag a little less used. Signed-off-by: Dmitry Safonov <dsafonov@virtuozzo.com> --- arch/x86/kernel/sys_x86_64.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/arch/x86/kernel/sys_x86_64.c b/arch/x86/kernel/sys_x86_64.c index 90be0839441d..533e879e9cdf 100644 --- a/arch/x86/kernel/sys_x86_64.c +++ b/arch/x86/kernel/sys_x86_64.c @@ -101,7 +101,7 @@ SYSCALL_DEFINE6(mmap, unsigned long, addr, unsigned long, len, static void find_start_end(unsigned long flags, unsigned long *begin, unsigned long *end) { - if (!test_thread_flag(TIF_ADDR32) && (flags & MAP_32BIT)) { + if (!in_compat_syscall() && (flags & MAP_32BIT)) { /* This is usually used needed to map code in small model, so it needs to be in the first 31bit. Limit it to that. This means we need to move the @@ -195,7 +195,7 @@ arch_get_unmapped_area_topdown(struct file *filp, const unsigned long addr0, return addr; /* for MAP_32BIT mappings we force the legacy mmap base */ - if (!test_thread_flag(TIF_ADDR32) && (flags & MAP_32BIT)) + if (!in_compat_syscall() && (flags & MAP_32BIT)) goto bottomup; /* requesting a specific address */ -- 2.11.0
WARNING: multiple messages have this Message-ID (diff)
From: Dmitry Safonov <dsafonov@virtuozzo.com> To: linux-kernel@vger.kernel.org Cc: 0x7f454c46@gmail.com, Dmitry Safonov <dsafonov@virtuozzo.com>, Thomas Gleixner <tglx@linutronix.de>, Ingo Molnar <mingo@redhat.com>, "H. Peter Anvin" <hpa@zytor.com>, Andy Lutomirski <luto@kernel.org>, Borislav Petkov <bp@suse.de>, x86@kernel.org, linux-mm@kvack.org Subject: [PATCHv4 4/5] x86/mm: check in_compat_syscall() instead TIF_ADDR32 for mmap(MAP_32BIT) Date: Mon, 30 Jan 2017 15:04:31 +0300 [thread overview] Message-ID: <20170130120432.6716-5-dsafonov@virtuozzo.com> (raw) In-Reply-To: <20170130120432.6716-1-dsafonov@virtuozzo.com> At this momet, logic in arch_get_unmapped_area{,_topdown} for mmaps with MAP_32BIT flag checks TIF_ADDR32 which means: o if 32-bit ELF changes mode to 64-bit on x86_64 and then tries to mmap() with MAP_32BIT it'll result in addr over 4Gb (as default is top-down allocation) o if 64-bit ELF changes mode to 32-bit and tries mmap() with MAP_32BIT, it'll allocate only memory in 1GB space: [0x40000000, 0x80000000). Fix it by handeling MAP_32BIT in 64-bit syscalls only. As a little bonus it'll make thread flag a little less used. Signed-off-by: Dmitry Safonov <dsafonov@virtuozzo.com> --- arch/x86/kernel/sys_x86_64.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/arch/x86/kernel/sys_x86_64.c b/arch/x86/kernel/sys_x86_64.c index 90be0839441d..533e879e9cdf 100644 --- a/arch/x86/kernel/sys_x86_64.c +++ b/arch/x86/kernel/sys_x86_64.c @@ -101,7 +101,7 @@ SYSCALL_DEFINE6(mmap, unsigned long, addr, unsigned long, len, static void find_start_end(unsigned long flags, unsigned long *begin, unsigned long *end) { - if (!test_thread_flag(TIF_ADDR32) && (flags & MAP_32BIT)) { + if (!in_compat_syscall() && (flags & MAP_32BIT)) { /* This is usually used needed to map code in small model, so it needs to be in the first 31bit. Limit it to that. This means we need to move the @@ -195,7 +195,7 @@ arch_get_unmapped_area_topdown(struct file *filp, const unsigned long addr0, return addr; /* for MAP_32BIT mappings we force the legacy mmap base */ - if (!test_thread_flag(TIF_ADDR32) && (flags & MAP_32BIT)) + if (!in_compat_syscall() && (flags & MAP_32BIT)) goto bottomup; /* requesting a specific address */ -- 2.11.0 -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@kvack.org"> email@kvack.org </a>
next prev parent reply other threads:[~2017-01-30 12:06 UTC|newest] Thread overview: 49+ messages / expand[flat|nested] mbox.gz Atom feed top 2017-01-30 12:04 [PATCHv4 0/5] Fix compatible mmap() return pointer over 4Gb Dmitry Safonov 2017-01-30 12:04 ` Dmitry Safonov 2017-01-30 12:04 ` [PATCHv4 1/5] x86/mm: split arch_mmap_rnd() on compat/native versions Dmitry Safonov 2017-01-30 12:04 ` Dmitry Safonov 2017-02-09 13:55 ` Borislav Petkov 2017-02-09 23:06 ` Andy Lutomirski 2017-02-09 23:06 ` Andy Lutomirski 2017-02-10 20:10 ` Thomas Gleixner 2017-02-10 20:10 ` Thomas Gleixner 2017-02-10 20:25 ` Borislav Petkov 2017-02-10 20:25 ` Borislav Petkov 2017-02-10 21:28 ` Dmitry Safonov 2017-02-10 21:28 ` Dmitry Safonov 2017-02-11 8:23 ` Thomas Gleixner 2017-02-11 8:23 ` Thomas Gleixner 2017-02-13 11:12 ` Dmitry Safonov 2017-02-13 11:12 ` Dmitry Safonov 2017-02-13 11:22 ` Thomas Gleixner 2017-02-13 11:22 ` Thomas Gleixner 2017-01-30 12:04 ` [PATCHv4 2/5] x86/mm: introduce mmap{,_legacy}_base Dmitry Safonov 2017-01-30 12:04 ` Dmitry Safonov 2017-02-11 14:13 ` Thomas Gleixner 2017-02-11 14:13 ` Thomas Gleixner 2017-02-13 13:02 ` Dmitry Safonov 2017-02-13 13:02 ` Dmitry Safonov 2017-02-13 13:13 ` Thomas Gleixner 2017-02-13 13:13 ` Thomas Gleixner 2017-02-13 14:37 ` Dmitry Safonov 2017-02-13 14:37 ` Dmitry Safonov 2017-02-13 15:35 ` Thomas Gleixner 2017-02-13 15:35 ` Thomas Gleixner 2017-01-30 12:04 ` [PATCHv4 3/5] x86/mm: fix 32-bit mmap() for 64-bit ELF Dmitry Safonov 2017-01-30 12:04 ` Dmitry Safonov 2017-02-11 19:49 ` Thomas Gleixner 2017-02-11 19:49 ` Thomas Gleixner 2017-02-14 15:24 ` Dmitry Safonov 2017-02-14 15:24 ` Dmitry Safonov 2017-01-30 12:04 ` Dmitry Safonov [this message] 2017-01-30 12:04 ` [PATCHv4 4/5] x86/mm: check in_compat_syscall() instead TIF_ADDR32 for mmap(MAP_32BIT) Dmitry Safonov 2017-02-11 20:13 ` Thomas Gleixner 2017-02-11 20:13 ` Thomas Gleixner 2017-02-14 16:11 ` Dmitry Safonov 2017-02-14 16:11 ` Dmitry Safonov 2017-02-14 16:14 ` Dmitry Safonov 2017-02-14 16:14 ` Dmitry Safonov 2017-01-30 12:04 ` [PATCHv4 5/5] selftests/x86: add test to check compat mmap() return addr Dmitry Safonov 2017-01-30 12:04 ` Dmitry Safonov 2017-02-06 16:46 ` [PATCHv4 0/5] Fix compatible mmap() return pointer over 4Gb Dmitry Safonov 2017-02-06 16:46 ` Dmitry Safonov
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