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Thu, 10 Apr 2025 08:31:32 +0000 (UTC) Received: from dovecot-director2.suse.de ([2a07:de40:b281:106:10:150:64:167]) by imap1.dmz-prg2.suse.org with ESMTPSA id DwDwJ+SB92cdCgAAD6G6ig (envelope-from ); Thu, 10 Apr 2025 08:31:32 +0000 Date: Thu, 10 Apr 2025 10:31:21 +0200 From: Oscar Salvador To: Baoquan He Cc: linux-mm@kvack.org, akpm@linux-foundation.org, david@redhat.com, yanjun.zhu@linux.dev, linux-kernel@vger.kernel.org Subject: Re: [PATCH v4 1/4] mm/gup: fix wrongly calculated returned value in fault_in_safe_writeable() Message-ID: References: <20250410035717.473207-1-bhe@redhat.com> <20250410035717.473207-2-bhe@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20250410035717.473207-2-bhe@redhat.com> X-Rspamd-Queue-Id: E130318000C X-Stat-Signature: 9c3z5ds4s8j7fh77mu5ysy6a5o6rpfue X-Rspam-User: X-Rspamd-Server: rspam12 X-HE-Tag: 1744273894-823334 X-HE-Meta: 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 jlQ1Bpf0 oO31K5ZVdL9xmbON8xKPVBz626rRyvh8/hJVABJYn/5fanOxol/UuSsY32n1pfB9tDTqcfCJ6E++Lxb8JGneYUm5NAJIR+F4WogtN4K90I5qYVjCiINzuOyH9R2ZAui3yfQubjgMKzBwmu1/Kn14rFC1aCHrR4PCYXYOpBkFMsq3o8pJIOSRzsz7DiI3ZUFcJ8SZaIjwUhkaMf9yEgwvHC+q4uTOsvnleITL5erv1kqTb9DBdxN6zT88txyyh/nnOOOyuqlAXHrexa/V5mQNw4gj8uONNU2akaPv04HnEKS8RA3PiO+Ys1PrxaxeTBWp6G/IQbhNIdDzlwhQ= 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: List-Subscribe: List-Unsubscribe: On Thu, Apr 10, 2025 at 11:57:14AM +0800, Baoquan He wrote: > Not like fault_in_readable() or fault_in_writeable(), in > fault_in_safe_writeable() local variable 'start' is increased page > by page to loop till the whole address range is handled. However, > it mistakenly calcalates the size of handled range with 'uaddr - start'. > > Fix it here. > > Signed-off-by: Baoquan He > Fixes: fe673d3f5bf1 ("mm: gup: make fault_in_safe_writeable() use fixup_user_fault()") Reviewed-by: Oscar Salvador > --- > mm/gup.c | 4 ++-- > 1 file changed, 2 insertions(+), 2 deletions(-) > > diff --git a/mm/gup.c b/mm/gup.c > index 92351e2fa876..84461d384ae2 100644 > --- a/mm/gup.c > +++ b/mm/gup.c > @@ -2207,8 +2207,8 @@ size_t fault_in_safe_writeable(const char __user *uaddr, size_t size) > } while (start != end); > mmap_read_unlock(mm); > > - if (size > (unsigned long)uaddr - start) > - return size - ((unsigned long)uaddr - start); > + if (size > start - (unsigned long)uaddr) > + return size - (start - (unsigned long)uaddr); > return 0; > } > EXPORT_SYMBOL(fault_in_safe_writeable); > -- > 2.41.0 > -- Oscar Salvador SUSE Labs