| Message ID | 20200327171030.30625-1-natechancellor@gmail.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | [-next] fanotify: Fix the checks in fanotify_fsid_equal | expand |
On Fri, Mar 27, 2020 at 10:10 AM Nathan Chancellor <natechancellor@gmail.com> wrote: > > Clang warns: > > fs/notify/fanotify/fanotify.c:28:23: warning: self-comparison always > evaluates to true [-Wtautological-compare] > return fsid1->val[0] == fsid1->val[0] && fsid2->val[1] == fsid2->val[1]; > ^ > fs/notify/fanotify/fanotify.c:28:57: warning: self-comparison always > evaluates to true [-Wtautological-compare] > return fsid1->val[0] == fsid1->val[0] && fsid2->val[1] == fsid2->val[1]; > ^ > 2 warnings generated. > > The intention was clearly to compare val[0] and val[1] in the two > different fsid structs. Fix it otherwise this function always returns > true. > > Fixes: afc894c784c8 ("fanotify: Store fanotify handles differently") > Link: https://github.com/ClangBuiltLinux/linux/issues/952 > Signed-off-by: Nathan Chancellor <natechancellor@gmail.com> Thanks for the patch. Subtle bugs that are off by one character have always been hard for me to spot! Reviewed-by: Nick Desaulniers <ndesaulniers@google.com> > --- > fs/notify/fanotify/fanotify.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/fs/notify/fanotify/fanotify.c b/fs/notify/fanotify/fanotify.c > index 7a889da1ee12..cb54ecdb3fb9 100644 > --- a/fs/notify/fanotify/fanotify.c > +++ b/fs/notify/fanotify/fanotify.c > @@ -25,7 +25,7 @@ static bool fanotify_path_equal(struct path *p1, struct path *p2) > static inline bool fanotify_fsid_equal(__kernel_fsid_t *fsid1, > __kernel_fsid_t *fsid2) > { > - return fsid1->val[0] == fsid1->val[0] && fsid2->val[1] == fsid2->val[1]; > + return fsid1->val[0] == fsid2->val[0] && fsid1->val[1] == fsid2->val[1]; > } > > static bool fanotify_fh_equal(struct fanotify_fh *fh1, > --
On Fri, Mar 27, 2020 at 8:10 PM Nathan Chancellor <natechancellor@gmail.com> wrote: > > Clang warns: > > fs/notify/fanotify/fanotify.c:28:23: warning: self-comparison always > evaluates to true [-Wtautological-compare] > return fsid1->val[0] == fsid1->val[0] && fsid2->val[1] == fsid2->val[1]; > ^ > fs/notify/fanotify/fanotify.c:28:57: warning: self-comparison always > evaluates to true [-Wtautological-compare] > return fsid1->val[0] == fsid1->val[0] && fsid2->val[1] == fsid2->val[1]; > ^ > 2 warnings generated. > > The intention was clearly to compare val[0] and val[1] in the two > different fsid structs. Fix it otherwise this function always returns > true. > > Fixes: afc894c784c8 ("fanotify: Store fanotify handles differently") > Link: https://github.com/ClangBuiltLinux/linux/issues/952 > Signed-off-by: Nathan Chancellor <natechancellor@gmail.com> > --- Ouch! Good catch! It would have been quite hard to catch this with tests as non equal fsid and equal fid are quite rare in the wild. I will try to write some test with mounts of cloned loop devs. Thanks, Amir.
On Fri 27-03-20 10:10:30, Nathan Chancellor wrote: > Clang warns: > > fs/notify/fanotify/fanotify.c:28:23: warning: self-comparison always > evaluates to true [-Wtautological-compare] > return fsid1->val[0] == fsid1->val[0] && fsid2->val[1] == fsid2->val[1]; > ^ > fs/notify/fanotify/fanotify.c:28:57: warning: self-comparison always > evaluates to true [-Wtautological-compare] > return fsid1->val[0] == fsid1->val[0] && fsid2->val[1] == fsid2->val[1]; > ^ > 2 warnings generated. > > The intention was clearly to compare val[0] and val[1] in the two > different fsid structs. Fix it otherwise this function always returns > true. > > Fixes: afc894c784c8 ("fanotify: Store fanotify handles differently") > Link: https://github.com/ClangBuiltLinux/linux/issues/952 > Signed-off-by: Nathan Chancellor <natechancellor@gmail.com> Thanks for the fix! That's a good catch that would have been pain to debug! I've applied it to my tree. Honza > --- > fs/notify/fanotify/fanotify.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/fs/notify/fanotify/fanotify.c b/fs/notify/fanotify/fanotify.c > index 7a889da1ee12..cb54ecdb3fb9 100644 > --- a/fs/notify/fanotify/fanotify.c > +++ b/fs/notify/fanotify/fanotify.c > @@ -25,7 +25,7 @@ static bool fanotify_path_equal(struct path *p1, struct path *p2) > static inline bool fanotify_fsid_equal(__kernel_fsid_t *fsid1, > __kernel_fsid_t *fsid2) > { > - return fsid1->val[0] == fsid1->val[0] && fsid2->val[1] == fsid2->val[1]; > + return fsid1->val[0] == fsid2->val[0] && fsid1->val[1] == fsid2->val[1]; > } > > static bool fanotify_fh_equal(struct fanotify_fh *fh1, > -- > 2.26.0 >
diff --git a/fs/notify/fanotify/fanotify.c b/fs/notify/fanotify/fanotify.c index 7a889da1ee12..cb54ecdb3fb9 100644 --- a/fs/notify/fanotify/fanotify.c +++ b/fs/notify/fanotify/fanotify.c @@ -25,7 +25,7 @@ static bool fanotify_path_equal(struct path *p1, struct path *p2) static inline bool fanotify_fsid_equal(__kernel_fsid_t *fsid1, __kernel_fsid_t *fsid2) { - return fsid1->val[0] == fsid1->val[0] && fsid2->val[1] == fsid2->val[1]; + return fsid1->val[0] == fsid2->val[0] && fsid1->val[1] == fsid2->val[1]; } static bool fanotify_fh_equal(struct fanotify_fh *fh1,
Clang warns: fs/notify/fanotify/fanotify.c:28:23: warning: self-comparison always evaluates to true [-Wtautological-compare] return fsid1->val[0] == fsid1->val[0] && fsid2->val[1] == fsid2->val[1]; ^ fs/notify/fanotify/fanotify.c:28:57: warning: self-comparison always evaluates to true [-Wtautological-compare] return fsid1->val[0] == fsid1->val[0] && fsid2->val[1] == fsid2->val[1]; ^ 2 warnings generated. The intention was clearly to compare val[0] and val[1] in the two different fsid structs. Fix it otherwise this function always returns true. Fixes: afc894c784c8 ("fanotify: Store fanotify handles differently") Link: https://github.com/ClangBuiltLinux/linux/issues/952 Signed-off-by: Nathan Chancellor <natechancellor@gmail.com> --- fs/notify/fanotify/fanotify.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)