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[86.156.84.164]) by smtp.gmail.com with ESMTPSA id f24-20020a7bc8d8000000b003eb596cbc54sm1772219wml.0.2023.03.23.05.05.28 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 23 Mar 2023 05:05:28 -0700 (PDT) Date: Thu, 23 Mar 2023 12:05:28 +0000 From: Lorenzo Stoakes To: Arnd Bergmann Cc: Andrew Morton , Arnd Bergmann , Uladzislau Rezki , Christoph Hellwig , Baoquan He , David Hildenbrand , Andrey Konovalov , linux-mm@kvack.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH 2/3] mm: vmalloc: fix vmap_ram_vread_iter() return value Message-ID: <0958ea78-c299-478b-8840-f1cafd893771@lucifer.local> References: <20230323115903.1483668-1-arnd@kernel.org> <20230323115903.1483668-2-arnd@kernel.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20230323115903.1483668-2-arnd@kernel.org> X-Rspam-User: X-Rspamd-Server: rspam04 X-Rspamd-Queue-Id: 1B035C0025 X-Stat-Signature: fyw1oc5118z9c6txkeg57h7j7izqycas X-HE-Tag: 1679573130-984670 X-HE-Meta: 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 Kb8XqQPk 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 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On Thu, Mar 23, 2023 at 12:58:35PM +0100, Arnd Bergmann wrote: > From: Arnd Bergmann > > The error handling in vmap_ram_vread_iter() can return an > uninitialized value in some cases: > > mm/vmalloc.c:3539:6: error: variable 'remains' is used uninitialized whenever 'if' condition is true [-Werror,-Wsometimes-uninitialized] > if (!vb) > ^~~ > mm/vmalloc.c:3587:17: note: uninitialized use occurs here > return count - remains + zero_iter(iter, remains); > ^~~~~~~ > > Move the initialization up a few lines. > > Fixes: d9cab54f7737 ("mm: vmalloc: convert vread() to vread_iter()") > Signed-off-by: Arnd Bergmann > --- > mm/vmalloc.c | 3 +-- > 1 file changed, 1 insertion(+), 2 deletions(-) > > diff --git a/mm/vmalloc.c b/mm/vmalloc.c > index ebfa1e9fe6f9..fb216495fe5a 100644 > --- a/mm/vmalloc.c > +++ b/mm/vmalloc.c > @@ -3521,7 +3521,7 @@ static size_t vmap_ram_vread_iter(struct iov_iter *iter, const char *addr, > struct vmap_block *vb; > unsigned long offset; > unsigned int rs, re; > - size_t remains, n; > + size_t remains = count, n; > > /* > * If it's area created by vm_map_ram() interface directly, but > @@ -3545,7 +3545,6 @@ static size_t vmap_ram_vread_iter(struct iov_iter *iter, const char *addr, > goto finished_zero; > } > > - remains = count; > for_each_set_bitrange(rs, re, vb->used_map, VMAP_BBMAP_BITS) { > size_t copied; > > -- > 2.39.2 > > This was also already fixed in a more recent version of this patch set, in v5 I believe. Again apologies for this! Latest version at https://lore.kernel.org/all/cover.1679566220.git.lstoakes@gmail.com