kernel.git/arch/sparc/kernel, branch linux-4.11.y

mm: larger stack guard gap, between vmas

2017-06-24T05:06:22Z

commit 1be7107fbe18eed3e319a6c3e83c78254b693acb upstream. Stack guard page is a useful feature to reduce a risk of stack smashing into a different mapping. We have been using a single page gap which is sufficient to prevent having stack adjacent to a different mapping. But this seems to be insufficient in the light of the stack usage in userspace. E.g. glibc uses as large as 64kB alloca() in many commonly used functions. Others use constructs liks gid_t buffer[NGROUPS_MAX] which is 256kB or stack strings with MAX_ARG_STRLEN. This will become especially dangerous for suid binaries and the default no limit for the stack size limit because those applications can be tricked to consume a large portion of the stack and a single glibc call could jump over the guard page. These attacks are not theoretical, unfortunatelly. Make those attacks less probable by increasing the stack guard gap to 1MB (on systems with 4k pages; but make it depend on the page size because systems with larger base pages might cap stack allocations in the PAGE_SIZE units) which should cover larger alloca() and VLA stack allocations. It is obviously not a full fix because the problem is somehow inherent, but it should reduce attack space a lot. One could argue that the gap size should be configurable from userspace, but that can be done later when somebody finds that the new 1MB is wrong for some special case applications. For now, add a kernel command line option (stack_guard_gap) to specify the stack gap size (in page units). Implementation wise, first delete all the old code for stack guard page: because although we could get away with accounting one extra page in a stack vma, accounting a larger gap can break userspace - case in point, a program run with "ulimit -S -v 20000" failed when the 1MB gap was counted for RLIMIT_AS; similar problems could come with RLIMIT_MLOCK and strict non-overcommit mode. Instead of keeping gap inside the stack vma, maintain the stack guard gap as a gap between vmas: using vm_start_gap() in place of vm_start (or vm_end_gap() in place of vm_end if VM_GROWSUP) in just those few places which need to respect the gap - mainly arch_get_unmapped_area(), and and the vma tree's subtree_gap support for that. Original-patch-by: Oleg Nesterov Original-patch-by: Michal Hocko Signed-off-by: Hugh Dickins Acked-by: Michal Hocko Tested-by: Helge Deller # parisc Signed-off-by: Linus Torvalds [wt: backport to 4.11: adjust context] Signed-off-by: Willy Tarreau Signed-off-by: Greg Kroah-Hartman

arch/sparc: support NR_CPUS = 4096

2017-06-14T13:07:36Z

[ Upstream commit c79a13734d104b5b147d7cb0870276ccdd660dae ] Linux SPARC64 limits NR_CPUS to 4064 because init_cpu_send_mondo_info() only allocates a single page for NR_CPUS mondo entries. Thus we cannot use all 4096 CPUs on some SPARC platforms. To fix, allocate (2^order) pages where order is set according to the size of cpu_list for possible cpus. Since cpu_list_pa and cpu_mondo_block_pa are not used in asm code, there are no imm13 offsets from the base PA that will break because they can only reach one page. Orabug: 25505750 Signed-off-by: Jane Chu Reviewed-by: Bob Picco Reviewed-by: Atish Patra Signed-off-by: David S. Miller Signed-off-by: Greg Kroah-Hartman

sparc64: delete old wrap code

2017-06-14T13:07:36Z

[ Upstream commit 0197e41ce70511dc3b71f7fefa1a676e2b5cd60b ] The old method that is using xcall and softint to get new context id is deleted, as it is replaced by a method of using per_cpu_secondary_mm without xcall to perform the context wrap. Signed-off-by: Pavel Tatashin Reviewed-by: Bob Picco Reviewed-by: Steven Sistare Signed-off-by: David S. Miller Signed-off-by: Greg Kroah-Hartman

sparc: Machine description indices can vary

2017-06-14T13:07:35Z

[ Upstream commit c982aa9c304bf0b9a7522fd118fed4afa5a0263c ] VIO devices were being looked up by their index in the machine description node block, but this often varies over time as devices are added and removed. Instead, store the ID and look up using the type, config handle and ID. Signed-off-by: James Clarke Bugzilla: https://bugzilla.kernel.org/show_bug.cgi?id=112541 Signed-off-by: David S. Miller Signed-off-by: Greg Kroah-Hartman

sparc64: mm: fix copy_tsb to correctly copy huge page TSBs

2017-06-14T13:07:35Z

[ Upstream commit 654f4807624a657f364417c2a7454f0df9961734 ] When a TSB grows beyond its current capacity, a new TSB is allocated and copy_tsb is called to copy entries from the old TSB to the new. A hash shift based on page size is used to calculate the index of an entry in the TSB. copy_tsb has hard coded PAGE_SHIFT in these calculations. However, for huge page TSBs the value REAL_HPAGE_SHIFT should be used. As a result, when copy_tsb is called for a huge page TSB the entries are placed at the incorrect index in the newly allocated TSB. When doing hardware table walk, the MMU does not match these entries and we end up in the TSB miss handling code. This code will then create and write an entry to the correct index in the TSB. We take a performance hit for the table walk miss and recreation of these entries. Pass a new parameter to copy_tsb that is the page size shift to be used when copying the TSB. Suggested-by: Anthony Yznaga Signed-off-by: Mike Kravetz Signed-off-by: David S. Miller Signed-off-by: Greg Kroah-Hartman

sparc/ftrace: Fix ftrace graph time measurement

2017-06-07T10:10:05Z

[ Upstream commit 48078d2dac0a26f84f5f3ec704f24f7c832cce14 ] The ftrace function_graph time measurements of a given function is not accurate according to those recorded by ftrace using the function filters. This change pulls the x86_64 fix from 'commit 722b3c746953 ("ftrace/graph: Trace function entry before updating index")' into the sparc specific prepare_ftrace_return which stops ftrace from counting interrupted tasks in the time measurement. Example measurements for select_task_rq_fair running "hackbench 100 process 1000": | tracing/trace_stat/function0 | function_graph Before patch | 2.802 us | 4.255 us After patch | 2.749 us | 3.094 us Signed-off-by: Liam R. Howlett Signed-off-by: David S. Miller Signed-off-by: Greg Kroah-Hartman

sparc64: fix fault handling in NGbzero.S and GENbzero.S

2017-05-14T12:06:01Z

commit 3c7f62212018b904ae17f5636ead18a4dca3a88f upstream. When any of the functions contained in NGbzero.S and GENbzero.S vector through *bzero_from_clear_user, we may end up taking a fault when executing one of the store alternate address space instructions. If this happens, the exception handler does not restore the %asi register. This commit fixes the issue by introducing a new exception handler that ensures the %asi register is restored when a fault is handled. Orabug: 25577560 Signed-off-by: Dave Aldridge Reviewed-by: Rob Gardner Reviewed-by: Babu Moger Signed-off-by: David S. Miller Signed-off-by: Greg Kroah-Hartman

sparc: Update syscall tables.

2017-04-24T01:28:55Z

Hook up statx. Ignore pkeys system calls, we don't have protection keeys on SPARC. Signed-off-by: David S. Miller

sparc64: Fill in rest of HAVE_REGS_AND_STACK_ACCESS_API

2017-04-24T00:15:51Z

This lets us enable KPROBE_EVENTS. Signed-off-by: David S. Miller

Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/sparc

2017-04-08T08:42:05Z

Pull sparc fixes from David Miller: "Several fixes here, mostly having to due with either build errors or memory corruptions depending upon whether you have THP enabled or not" * git://git.kernel.org/pub/scm/linux/kernel/git/davem/sparc: sparc: remove unused wp_works_ok macro sparc32: Export vac_cache_size to fix build error sparc64: Fix memory corruption when THP is enabled sparc64: Fix kernel panic due to erroneous #ifdef surrounding pmd_write() arch/sparc: Avoid DCTI Couples sparc64: kern_addr_valid regression sparc64: Add support for 2G hugepages sparc64: Fix size check in huge_pte_alloc