diff --git a/debian/changelog b/debian/changelog index 67ae7ed64..13ab99802 100644 --- a/debian/changelog +++ b/debian/changelog @@ -3,10 +3,11 @@ linux-2.6 (2.6.35-1~experimental.2) experimental; urgency=low * images: Nuke modules.devname on removal. (closes: #590607) * Add stable 2.6.35.1 and 2.6.35.2. * mm: fix page table unmap for stack guard page properly. + * mm: fix up some user-visible effects of the stack guard page. * config.loongson-2f: Enable USB and RTC for loongson-2f. Thanks Geert Stappers (closes: #583689) - -- maximilian attems Mon, 16 Aug 2010 22:31:11 +0200 + -- maximilian attems Mon, 16 Aug 2010 23:49:32 +0200 linux-2.6 (2.6.35-1~experimental.1) experimental; urgency=low diff --git a/debian/patches/bugfix/all/mm-fix-up-some-user-visible-effects-of-the-stack-gua.patch b/debian/patches/bugfix/all/mm-fix-up-some-user-visible-effects-of-the-stack-gua.patch new file mode 100644 index 000000000..a354ae362 --- /dev/null +++ b/debian/patches/bugfix/all/mm-fix-up-some-user-visible-effects-of-the-stack-gua.patch @@ -0,0 +1,91 @@ +From d7824370e26325c881b665350ce64fb0a4fde24a Mon Sep 17 00:00:00 2001 +From: Linus Torvalds +Date: Sun, 15 Aug 2010 11:35:52 -0700 +Subject: [PATCH] mm: fix up some user-visible effects of the stack guard page +MIME-Version: 1.0 +Content-Type: text/plain; charset=UTF-8 +Content-Transfer-Encoding: 8bit + +This commit makes the stack guard page somewhat less visible to user +space. It does this by: + + - not showing the guard page in /proc//maps + + It looks like lvm-tools will actually read /proc/self/maps to figure + out where all its mappings are, and effectively do a specialized + "mlockall()" in user space. By not showing the guard page as part of + the mapping (by just adding PAGE_SIZE to the start for grows-up + pages), lvm-tools ends up not being aware of it. + + - by also teaching the _real_ mlock() functionality not to try to lock + the guard page. + + That would just expand the mapping down to create a new guard page, + so there really is no point in trying to lock it in place. + +It would perhaps be nice to show the guard page specially in +/proc//maps (or at least mark grow-down segments some way), but +let's not open ourselves up to more breakage by user space from programs +that depends on the exact deails of the 'maps' file. + +Special thanks to Henrique de Moraes Holschuh for diving into lvm-tools +source code to see what was going on with the whole new warning. + +Reported-and-tested-by: François Valenduc +Cc: stable@kernel.org +Signed-off-by: Linus Torvalds +--- + fs/proc/task_mmu.c | 8 +++++++- + mm/mlock.c | 8 ++++++++ + 2 files changed, 15 insertions(+), 1 deletions(-) + +diff --git a/fs/proc/task_mmu.c b/fs/proc/task_mmu.c +index aea1d3f..439fc1f 100644 +--- a/fs/proc/task_mmu.c ++++ b/fs/proc/task_mmu.c +@@ -210,6 +210,7 @@ static void show_map_vma(struct seq_file *m, struct vm_area_struct *vma) + int flags = vma->vm_flags; + unsigned long ino = 0; + unsigned long long pgoff = 0; ++ unsigned long start; + dev_t dev = 0; + int len; + +@@ -220,8 +221,13 @@ static void show_map_vma(struct seq_file *m, struct vm_area_struct *vma) + pgoff = ((loff_t)vma->vm_pgoff) << PAGE_SHIFT; + } + ++ /* We don't show the stack guard page in /proc/maps */ ++ start = vma->vm_start; ++ if (vma->vm_flags & VM_GROWSDOWN) ++ start += PAGE_SIZE; ++ + seq_printf(m, "%08lx-%08lx %c%c%c%c %08llx %02x:%02x %lu %n", +- vma->vm_start, ++ start, + vma->vm_end, + flags & VM_READ ? 'r' : '-', + flags & VM_WRITE ? 'w' : '-', +diff --git a/mm/mlock.c b/mm/mlock.c +index 3f82720..49e5e4c 100644 +--- a/mm/mlock.c ++++ b/mm/mlock.c +@@ -167,6 +167,14 @@ static long __mlock_vma_pages_range(struct vm_area_struct *vma, + if (vma->vm_flags & VM_WRITE) + gup_flags |= FOLL_WRITE; + ++ /* We don't try to access the guard page of a stack vma */ ++ if (vma->vm_flags & VM_GROWSDOWN) { ++ if (start == vma->vm_start) { ++ start += PAGE_SIZE; ++ nr_pages--; ++ } ++ } ++ + while (nr_pages > 0) { + int i; + +-- +1.7.1 + diff --git a/debian/patches/series/1~experimental.2 b/debian/patches/series/1~experimental.2 index fd2929f67..16938ab88 100644 --- a/debian/patches/series/1~experimental.2 +++ b/debian/patches/series/1~experimental.2 @@ -1,3 +1,4 @@ + bugfix/all/stable/2.6.35.1.patch + bugfix/all/stable/2.6.35.2.patch + bugfix/all/mm-fix-page-table-unmap-for-stack-guard-page-properl.patch ++ bugfix/all/mm-fix-up-some-user-visible-effects-of-the-stack-gua.patch