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Author: mpagano |
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Date: 2010-08-20 20:32:11 +0000 (Fri, 20 Aug 2010) |
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New Revision: 1761 |
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|
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Added: |
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genpatches-2.6/trunk/2.6.35/1805_fix-user-visible-effects-of-stack-guard-page.patch |
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Modified: |
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genpatches-2.6/trunk/2.6.35/0000_README |
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Log: |
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Patch to make the stack guard page somewhat less visible to user space |
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|
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Modified: genpatches-2.6/trunk/2.6.35/0000_README |
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=================================================================== |
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--- genpatches-2.6/trunk/2.6.35/0000_README 2010-08-20 20:17:25 UTC (rev 1760) |
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+++ genpatches-2.6/trunk/2.6.35/0000_README 2010-08-20 20:32:11 UTC (rev 1761) |
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@@ -51,6 +51,10 @@ |
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From: https://bugzilla.kernel.org/show_bug.cgi?id=16588 |
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Desc: Fix page table unmap for stack guard page properly |
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|
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+Patch: 1805_fix-user-visible-effects-of-stack-guard-page.patch |
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+From: http://bugs.gentoo.org/show_bug.cgi?id=333477 |
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+Desc: Make the stack guard page somewhat less visible to user space |
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+ |
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Patch: 2600_support-eject-dell-studio-1555.patch |
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From: http://bugs.gentoo.org/show_bug.cgi?id=333379 |
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Desc: Add support for eject key on Dell Studio 1555 |
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|
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Added: genpatches-2.6/trunk/2.6.35/1805_fix-user-visible-effects-of-stack-guard-page.patch |
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=================================================================== |
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--- genpatches-2.6/trunk/2.6.35/1805_fix-user-visible-effects-of-stack-guard-page.patch (rev 0) |
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+++ genpatches-2.6/trunk/2.6.35/1805_fix-user-visible-effects-of-stack-guard-page.patch 2010-08-20 20:32:11 UTC (rev 1761) |
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@@ -0,0 +1,85 @@ |
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+From: Linus Torvalds <torvalds@××××××××××××××××.org> |
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+Date: Sun, 15 Aug 2010 18:35:52 +0000 (-0700) |
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+Subject: mm: fix up some user-visible effects of the stack guard page |
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+X-Git-Tag: v2.6.36-rc1~5 |
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+X-Git-Url: http://git.kernel.org/?p=linux%2Fkernel%2Fgit%2Ftorvalds%2Flinux-2.6.git;a=commitdiff_plain;h=d7824370e26325c881b665350ce64fb0a4fde24a |
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+ |
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+mm: fix up some user-visible effects of the stack guard page |
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+ |
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+This commit makes the stack guard page somewhat less visible to user |
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+space. It does this by: |
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+ |
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+ - not showing the guard page in /proc/<pid>/maps |
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+ |
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+ It looks like lvm-tools will actually read /proc/self/maps to figure |
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+ out where all its mappings are, and effectively do a specialized |
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+ "mlockall()" in user space. By not showing the guard page as part of |
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+ the mapping (by just adding PAGE_SIZE to the start for grows-up |
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+ pages), lvm-tools ends up not being aware of it. |
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+ |
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+ - by also teaching the _real_ mlock() functionality not to try to lock |
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+ the guard page. |
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+ |
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+ That would just expand the mapping down to create a new guard page, |
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+ so there really is no point in trying to lock it in place. |
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+ |
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+It would perhaps be nice to show the guard page specially in |
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+/proc/<pid>/maps (or at least mark grow-down segments some way), but |
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+let's not open ourselves up to more breakage by user space from programs |
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+that depends on the exact deails of the 'maps' file. |
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+ |
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+Special thanks to Henrique de Moraes Holschuh for diving into lvm-tools |
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+source code to see what was going on with the whole new warning. |
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+ |
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+Reported-and-tested-by: François Valenduc <francois.valenduc@××××××××××.be |
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+Reported-by: Henrique de Moraes Holschuh <hmh@×××××××.br> |
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+Cc: stable@××××××.org |
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+Signed-off-by: Linus Torvalds <torvalds@××××××××××××××××.org> |
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+--- |
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+ |
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+diff --git a/fs/proc/task_mmu.c b/fs/proc/task_mmu.c |
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+index aea1d3f..439fc1f 100644 |
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+--- a/fs/proc/task_mmu.c |
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++++ b/fs/proc/task_mmu.c |
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+@@ -210,6 +210,7 @@ static void show_map_vma(struct seq_file *m, struct vm_area_struct *vma) |
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+ int flags = vma->vm_flags; |
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+ unsigned long ino = 0; |
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+ unsigned long long pgoff = 0; |
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++ unsigned long start; |
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+ dev_t dev = 0; |
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+ int len; |
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+ |
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+@@ -220,8 +221,13 @@ static void show_map_vma(struct seq_file *m, struct vm_area_struct *vma) |
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+ pgoff = ((loff_t)vma->vm_pgoff) << PAGE_SHIFT; |
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+ } |
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+ |
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++ /* We don't show the stack guard page in /proc/maps */ |
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++ start = vma->vm_start; |
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++ if (vma->vm_flags & VM_GROWSDOWN) |
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++ start += PAGE_SIZE; |
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++ |
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+ seq_printf(m, "%08lx-%08lx %c%c%c%c %08llx %02x:%02x %lu %n", |
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+- vma->vm_start, |
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++ start, |
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+ vma->vm_end, |
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+ flags & VM_READ ? 'r' : '-', |
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+ flags & VM_WRITE ? 'w' : '-', |
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+diff --git a/mm/mlock.c b/mm/mlock.c |
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+index 3f82720..49e5e4c 100644 |
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+--- a/mm/mlock.c |
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++++ b/mm/mlock.c |
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+@@ -167,6 +167,14 @@ static long __mlock_vma_pages_range(struct vm_area_struct *vma, |
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+ if (vma->vm_flags & VM_WRITE) |
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+ gup_flags |= FOLL_WRITE; |
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+ |
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++ /* We don't try to access the guard page of a stack vma */ |
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++ if (vma->vm_flags & VM_GROWSDOWN) { |
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++ if (start == vma->vm_start) { |
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++ start += PAGE_SIZE; |
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++ nr_pages--; |
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++ } |
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++ } |
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++ |
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+ while (nr_pages > 0) { |
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+ int i; |
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+ |
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