Messages in this thread Patch in this message | | | Date | Thu, 28 Mar 2024 09:53:55 -0500 | Subject | Re: [PATCH 3/9] rbd: avoid out-of-range warning | From | Alex Elder <> |
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On 3/28/24 9:30 AM, Arnd Bergmann wrote: > From: Arnd Bergmann <arnd@arndb.de> > > clang-14 points out that the range check is always true on 64-bit > architectures since a u32 is not greater than the allowed size: > > drivers/block/rbd.c:6079:17: error: result of comparison of constant 2305843009213693948 with expression of type 'u32' (aka 'unsigned int') is always false [-Werror,-Wtautological-constant-out-of-range-compare] w > ~~~~~~~~~~ ^ ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ > > This is harmless, so just change the type of the temporary to size_t > to shut up that warning.
This fixes the warning, but then the now size_t value is passed to ceph_decode_32_safe(), which implies a different type conversion. That too is not harmful, but...
Could we just cast the value in the comparison instead?
if ((size_t)snap_count > (SIZE_MAX - sizeof (struct ceph_snap_context))
You could drop the space between sizeof and ( while you're at it (I always used the space back then).
-Alex
> > Fixes: bb23e37acb2a ("rbd: refactor rbd_header_from_disk()") > Signed-off-by: Arnd Bergmann <arnd@arndb.de> > --- > drivers/block/rbd.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/drivers/block/rbd.c b/drivers/block/rbd.c > index 26ff5cd2bf0a..cb25ee513ada 100644 > --- a/drivers/block/rbd.c > +++ b/drivers/block/rbd.c > @@ -6062,7 +6062,7 @@ static int rbd_dev_v2_snap_context(struct rbd_device *rbd_dev, > void *p; > void *end; > u64 seq; > - u32 snap_count; > + size_t snap_count; > struct ceph_snap_context *snapc; > u32 i; >
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