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Fri, 07 Jul 2023 14:55:47 -0700 (PDT) Date: Fri, 7 Jul 2023 14:55:34 -0700 In-Reply-To: <20230707215540.2324998-1-axelrasmussen@google.com> Mime-Version: 1.0 References: <20230707215540.2324998-1-axelrasmussen@google.com> X-Mailer: git-send-email 2.41.0.255.g8b1d071c50-goog Message-ID: <20230707215540.2324998-3-axelrasmussen@google.com> Subject: [PATCH v4 2/8] mm: userfaultfd: check for start + len overflow in validate_range From: Axel Rasmussen To: Alexander Viro , Andrew Morton , Brian Geffon , Christian Brauner , David Hildenbrand , Gaosheng Cui , Huang Ying , Hugh Dickins , James Houghton , "Jan Alexander Steffens (heftig)" , Jiaqi Yan , Jonathan Corbet , Kefeng Wang , "Liam R. Howlett" , Miaohe Lin , Mike Kravetz , "Mike Rapoport (IBM)" , Muchun Song , Nadav Amit , Naoya Horiguchi , Peter Xu , Ryan Roberts , Shuah Khan , Suleiman Souhlal , Suren Baghdasaryan , "T.J. Alumbaugh" , Yu Zhao , ZhangPeng Cc: linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-mm@kvack.org, linux-kselftest@vger.kernel.org, Axel Rasmussen Content-Type: text/plain; charset="UTF-8" X-Rspamd-Server: rspam08 X-Rspamd-Queue-Id: 47189180007 X-Stat-Signature: sh5wbddsfqkk6ezp9tmtr9azczte53df X-Rspam-User: X-HE-Tag: 1688766947-880307 X-HE-Meta: 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 mwZ4aRyx 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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: Most userfaultfd ioctls take a `start + len` range as an argument. We have the validate_range helper to check that such ranges are valid. However, some (but not all!) ioctls *also* check that `start + len` doesn't wrap around (overflow). Just check for this in validate_range. This saves some repetitive code, and adds the check to some ioctls which weren't bothering to check for it before. Reviewed-by: Peter Xu Signed-off-by: Axel Rasmussen --- fs/userfaultfd.c | 15 +++------------ 1 file changed, 3 insertions(+), 12 deletions(-) diff --git a/fs/userfaultfd.c b/fs/userfaultfd.c index 7cecd49e078b..2e84684c46f0 100644 --- a/fs/userfaultfd.c +++ b/fs/userfaultfd.c @@ -1306,6 +1306,8 @@ static __always_inline int validate_range(struct mm_struct *mm, return -EINVAL; if (len > task_size - start) return -EINVAL; + if (start + len <= start) + return -EINVAL; return 0; } @@ -1760,14 +1762,8 @@ static int userfaultfd_copy(struct userfaultfd_ctx *ctx, ret = validate_range(ctx->mm, uffdio_copy.dst, uffdio_copy.len); if (ret) goto out; - /* - * double check for wraparound just in case. copy_from_user() - * will later check uffdio_copy.src + uffdio_copy.len to fit - * in the userland range. - */ + ret = -EINVAL; - if (uffdio_copy.src + uffdio_copy.len <= uffdio_copy.src) - goto out; if (uffdio_copy.mode & ~(UFFDIO_COPY_MODE_DONTWAKE|UFFDIO_COPY_MODE_WP)) goto out; if (uffdio_copy.mode & UFFDIO_COPY_MODE_WP) @@ -1927,11 +1923,6 @@ static int userfaultfd_continue(struct userfaultfd_ctx *ctx, unsigned long arg) goto out; ret = -EINVAL; - /* double check for wraparound just in case. */ - if (uffdio_continue.range.start + uffdio_continue.range.len <= - uffdio_continue.range.start) { - goto out; - } if (uffdio_continue.mode & ~(UFFDIO_CONTINUE_MODE_DONTWAKE | UFFDIO_CONTINUE_MODE_WP)) goto out; -- 2.41.0.255.g8b1d071c50-goog