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authorPeter Zijlstra <peterz@infradead.org>2019-10-21 15:11:49 +0200
committerIngo Molnar <mingo@kernel.org>2019-10-28 10:43:00 +0100
commit9a50dcaf0416a43e1fe411dc61a99c8333c90119 (patch)
tree5910dbf5fd26d3fa435cd76e482691ed1055cae3 /lib/ubsan.c
parent0f42c1ad44d437f75b840b572376fd538fbb9643 (diff)
downloadlinux-9a50dcaf0416a43e1fe411dc61a99c8333c90119.tar.bz2
ubsan, x86: Annotate and allow __ubsan_handle_shift_out_of_bounds() in uaccess regions
The new check_zeroed_user() function uses variable shifts inside of a user_access_begin()/user_access_end() section and that results in GCC emitting __ubsan_handle_shift_out_of_bounds() calls, even though through value range analysis it would be able to see that the UB in question is impossible. Annotate and whitelist this UBSAN function; continued use of user_access_begin()/user_access_end() will undoubtedly result in further uses of function. Reported-by: Randy Dunlap <rdunlap@infradead.org> Tested-by: Randy Dunlap <rdunlap@infradead.org> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Acked-by: Randy Dunlap <rdunlap@infradead.org> Acked-by: Christian Brauner <christian.brauner@ubuntu.com> Cc: Josh Poimboeuf <jpoimboe@redhat.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Stephen Rothwell <sfr@canb.auug.org.au> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: cyphar@cyphar.com Cc: keescook@chromium.org Cc: linux@rasmusvillemoes.dk Fixes: f5a1a536fa14 ("lib: introduce copy_struct_from_user() helper") Link: https://lkml.kernel.org/r/20191021131149.GA19358@hirez.programming.kicks-ass.net Signed-off-by: Ingo Molnar <mingo@kernel.org>
Diffstat (limited to 'lib/ubsan.c')
-rw-r--r--lib/ubsan.c5
1 files changed, 4 insertions, 1 deletions
diff --git a/lib/ubsan.c b/lib/ubsan.c
index e7d31735950d..0c4681118fcd 100644
--- a/lib/ubsan.c
+++ b/lib/ubsan.c
@@ -374,9 +374,10 @@ void __ubsan_handle_shift_out_of_bounds(struct shift_out_of_bounds_data *data,
struct type_descriptor *lhs_type = data->lhs_type;
char rhs_str[VALUE_LENGTH];
char lhs_str[VALUE_LENGTH];
+ unsigned long ua_flags = user_access_save();
if (suppress_report(&data->location))
- return;
+ goto out;
ubsan_prologue(&data->location, &flags);
@@ -402,6 +403,8 @@ void __ubsan_handle_shift_out_of_bounds(struct shift_out_of_bounds_data *data,
lhs_type->type_name);
ubsan_epilogue(&flags);
+out:
+ user_access_restore(ua_flags);
}
EXPORT_SYMBOL(__ubsan_handle_shift_out_of_bounds);