summaryrefslogtreecommitdiff
path: root/arch
diff options
context:
space:
mode:
authorKees Cook <keescook@chromium.org>2022-09-19 13:16:48 -0700
committerAndrew Morton <akpm@linux-foundation.org>2022-09-26 12:14:35 -0700
commit59298997df89e19aad426d4ae0a7e5037074da5a (patch)
treebd519e75ebd1570b528f9c7e3e2741c7d11055ea /arch
parent80e2b584f3abfc31c3fe5573007f0d1d10810fde (diff)
x86/uaccess: avoid check_object_size() in copy_from_user_nmi()
The check_object_size() helper under CONFIG_HARDENED_USERCOPY is designed to skip any checks where the length is known at compile time as a reasonable heuristic to avoid "likely known-good" cases. However, it can only do this when the copy_*_user() helpers are, themselves, inline too. Using find_vmap_area() requires taking a spinlock. The check_object_size() helper can call find_vmap_area() when the destination is in vmap memory. If show_regs() is called in interrupt context, it will attempt a call to copy_from_user_nmi(), which may call check_object_size() and then find_vmap_area(). If something in normal context happens to be in the middle of calling find_vmap_area() (with the spinlock held), the interrupt handler will hang forever. The copy_from_user_nmi() call is actually being called with a fixed-size length, so check_object_size() should never have been called in the first place. Given the narrow constraints, just replace the __copy_from_user_inatomic() call with an open-coded version that calls only into the sanitizers and not check_object_size(), followed by a call to raw_copy_from_user(). [akpm@linux-foundation.org: no instrument_copy_from_user() in my tree...] Link: https://lkml.kernel.org/r/20220919201648.2250764-1-keescook@chromium.org Link: https://lore.kernel.org/all/CAOUHufaPshtKrTWOz7T7QFYUNVGFm0JBjvM700Nhf9qEL9b3EQ@mail.gmail.com Fixes: 0aef499f3172 ("mm/usercopy: Detect vmalloc overruns") Signed-off-by: Kees Cook <keescook@chromium.org> Reported-by: Yu Zhao <yuzhao@google.com> Reported-by: Florian Lehner <dev@der-flo.net> Suggested-by: Andrew Morton <akpm@linux-foundation.org> Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org> Tested-by: Florian Lehner <dev@der-flo.net> Cc: Matthew Wilcox <willy@infradead.org> Cc: Josh Poimboeuf <jpoimboe@kernel.org> Cc: Dave Hansen <dave.hansen@linux.intel.com> Cc: <stable@vger.kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Diffstat (limited to 'arch')
-rw-r--r--arch/x86/lib/usercopy.c2
1 files changed, 1 insertions, 1 deletions
diff --git a/arch/x86/lib/usercopy.c b/arch/x86/lib/usercopy.c
index ad0139d25401..f1bb18617156 100644
--- a/arch/x86/lib/usercopy.c
+++ b/arch/x86/lib/usercopy.c
@@ -44,7 +44,7 @@ copy_from_user_nmi(void *to, const void __user *from, unsigned long n)
* called from other contexts.
*/
pagefault_disable();
- ret = __copy_from_user_inatomic(to, from, n);
+ ret = raw_copy_from_user(to, from, n);
pagefault_enable();
return ret;