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| author | Peter Zijlstra <peterz@infradead.org> | 2019-10-21 15:11:49 +0200 |
|---|---|---|
| committer | Ingo Molnar <mingo@kernel.org> | 2019-10-28 10:43:00 +0100 |
| commit | 9a50dcaf0416a43e1fe411dc61a99c8333c90119 (patch) | |
| tree | 5910dbf5fd26d3fa435cd76e482691ed1055cae3 /lib/ubsan.c | |
| parent | 0f42c1ad44d437f75b840b572376fd538fbb9643 (diff) | |
| download | lwn-9a50dcaf0416a43e1fe411dc61a99c8333c90119.tar.gz lwn-9a50dcaf0416a43e1fe411dc61a99c8333c90119.zip | |
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.c | 5 |
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); |