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| author | Gregory Price <gourry.memverge@gmail.com> | 2023-10-03 17:48:56 +0300 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2023-11-02 11:35:24 +0300 |
| commit | c9b066f6920d5e9d68258d0c708bef709406918c (patch) | |
| tree | 0db6eb9eed246c8831b9a2108156c9d296344c89 /mm | |
| parent | a6fbf025e3cf41b255b34bccc9a963c4eeb8c352 (diff) | |
| download | linux-c9b066f6920d5e9d68258d0c708bef709406918c.tar.xz | |
mm/migrate: fix do_pages_move for compat pointers
commit 229e2253766c7cdfe024f1fe280020cc4711087c upstream.
do_pages_move does not handle compat pointers for the page list.
correctly. Add in_compat_syscall check and appropriate get_user fetch
when iterating the page list.
It makes the syscall in compat mode (32-bit userspace, 64-bit kernel)
work the same way as the native 32-bit syscall again, restoring the
behavior before my broken commit 5b1b561ba73c ("mm: simplify
compat_sys_move_pages").
More specifically, my patch moved the parsing of the 'pages' array from
the main entry point into do_pages_stat(), which left the syscall
working correctly for the 'stat' operation (nodes = NULL), while the
'move' operation (nodes != NULL) is now missing the conversion and
interprets 'pages' as an array of 64-bit pointers instead of the
intended 32-bit userspace pointers.
It is possible that nobody noticed this bug because the few
applications that actually call move_pages are unlikely to run in
compat mode because of their large memory requirements, but this
clearly fixes a user-visible regression and should have been caught by
ltp.
Link: https://lkml.kernel.org/r/20231003144857.752952-1-gregory.price@memverge.com
Fixes: 5b1b561ba73c ("mm: simplify compat_sys_move_pages")
Signed-off-by: Gregory Price <gregory.price@memverge.com>
Reported-by: Arnd Bergmann <arnd@arndb.de>
Co-developed-by: Arnd Bergmann <arnd@arndb.de>
Cc: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'mm')
| -rw-r--r-- | mm/migrate.c | 14 |
1 files changed, 12 insertions, 2 deletions
diff --git a/mm/migrate.c b/mm/migrate.c index 8d5c0dc618a5..9372a826e6d0 100644 --- a/mm/migrate.c +++ b/mm/migrate.c @@ -1787,6 +1787,7 @@ static int do_pages_move(struct mm_struct *mm, nodemask_t task_nodes, const int __user *nodes, int __user *status, int flags) { + compat_uptr_t __user *compat_pages = (void __user *)pages; int current_node = NUMA_NO_NODE; LIST_HEAD(pagelist); int start, i; @@ -1800,8 +1801,17 @@ static int do_pages_move(struct mm_struct *mm, nodemask_t task_nodes, int node; err = -EFAULT; - if (get_user(p, pages + i)) - goto out_flush; + if (in_compat_syscall()) { + compat_uptr_t cp; + + if (get_user(cp, compat_pages + i)) + goto out_flush; + + p = compat_ptr(cp); + } else { + if (get_user(p, pages + i)) + goto out_flush; + } if (get_user(node, nodes + i)) goto out_flush; addr = (unsigned long)untagged_addr(p); |