From: Peilin Ye <yepeilin.cs@gmail.com> To: Dan Carpenter <dan.carpenter@oracle.com> Cc: Arnd Bergmann <arnd@arndb.de>, Greg Kroah-Hartman <gregkh@linuxfoundation.org>, linux-kernel-mentees@lists.linuxfoundation.org, "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org> Subject: Re: [Linux-kernel-mentees] [PATCH v3] media/v4l2-core: Fix kernel-infoleak in video_put_user() Date: Tue, 28 Jul 2020 09:13:28 -0400 [thread overview] Message-ID: <20200728131328.GA410244@PWN> (raw) In-Reply-To: <20200728094707.GF2571@kadam> On Tue, Jul 28, 2020 at 12:47:07PM +0300, Dan Carpenter wrote: > On Mon, Jul 27, 2020 at 06:33:57PM -0400, Peilin Ye wrote: > > On Mon, Jul 27, 2020 at 04:16:08PM +0300, Dan Carpenter wrote: > > > drivers/block/floppy.c:3132 raw_cmd_copyout() warn: check that 'cmd' doesn't leak information (struct has a hole after 'flags') > > > > (Removed some Cc: recipients from the list.) > > > > I'm not very sure, but I think this one is also a false positive. > > No, it's a potential bug. You're over thinking what Smatch is > complaining about. Arnd is right. > > 3123 static int raw_cmd_copyout(int cmd, void __user *param, > 3124 struct floppy_raw_cmd *ptr) > 3125 { > 3126 int ret; > 3127 > 3128 while (ptr) { > 3129 struct floppy_raw_cmd cmd = *ptr; > ^^^^^^^^^^ > The compiler can either do this assignment as an memcpy() or as a > series of struct member assignments. So the assignment can leave the > struct hole uninitialized. I see, I didn't realize this line could cause the issue. Thank you for pointing this out, I will do this then send a patch: diff --git a/drivers/block/floppy.c b/drivers/block/floppy.c index 09079aee8dc4..398c261fd174 100644 --- a/drivers/block/floppy.c +++ b/drivers/block/floppy.c @@ -3126,7 +3126,8 @@ static int raw_cmd_copyout(int cmd, void __user *param, int ret; while (ptr) { - struct floppy_raw_cmd cmd = *ptr; + struct floppy_raw_cmd cmd; + memcpy(&cmd, ptr, sizeof(cmd)); cmd.next = NULL; cmd.kernel_data = NULL; ret = copy_to_user(param, &cmd, sizeof(cmd)); Thank you, Peilin Ye > 3130 cmd.next = NULL; > 3131 cmd.kernel_data = NULL; > 3132 ret = copy_to_user(param, &cmd, sizeof(cmd)); > ^^^^ > potential info leak. > > 3133 if (ret) > 3134 return -EFAULT; > 3135 param += sizeof(struct floppy_raw_cmd); > 3136 if ((ptr->flags & FD_RAW_READ) && ptr->buffer_length) { > 3137 if (ptr->length >= 0 && > 3138 ptr->length <= ptr->buffer_length) { > 3139 long length = ptr->buffer_length - ptr->length; > 3140 ret = fd_copyout(ptr->data, ptr->kernel_data, > 3141 length); > 3142 if (ret) > 3143 return ret; > 3144 } > 3145 } > 3146 ptr = ptr->next; > 3147 } > 3148 > 3149 return 0; > 3150 } > > regards, > dan carpenter
WARNING: multiple messages have this Message-ID (diff)
From: Peilin Ye <yepeilin.cs@gmail.com> To: Dan Carpenter <dan.carpenter@oracle.com> Cc: linux-kernel-mentees@lists.linuxfoundation.org, "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>, Arnd Bergmann <arnd@arndb.de> Subject: Re: [Linux-kernel-mentees] [PATCH v3] media/v4l2-core: Fix kernel-infoleak in video_put_user() Date: Tue, 28 Jul 2020 09:13:28 -0400 [thread overview] Message-ID: <20200728131328.GA410244@PWN> (raw) In-Reply-To: <20200728094707.GF2571@kadam> On Tue, Jul 28, 2020 at 12:47:07PM +0300, Dan Carpenter wrote: > On Mon, Jul 27, 2020 at 06:33:57PM -0400, Peilin Ye wrote: > > On Mon, Jul 27, 2020 at 04:16:08PM +0300, Dan Carpenter wrote: > > > drivers/block/floppy.c:3132 raw_cmd_copyout() warn: check that 'cmd' doesn't leak information (struct has a hole after 'flags') > > > > (Removed some Cc: recipients from the list.) > > > > I'm not very sure, but I think this one is also a false positive. > > No, it's a potential bug. You're over thinking what Smatch is > complaining about. Arnd is right. > > 3123 static int raw_cmd_copyout(int cmd, void __user *param, > 3124 struct floppy_raw_cmd *ptr) > 3125 { > 3126 int ret; > 3127 > 3128 while (ptr) { > 3129 struct floppy_raw_cmd cmd = *ptr; > ^^^^^^^^^^ > The compiler can either do this assignment as an memcpy() or as a > series of struct member assignments. So the assignment can leave the > struct hole uninitialized. I see, I didn't realize this line could cause the issue. Thank you for pointing this out, I will do this then send a patch: diff --git a/drivers/block/floppy.c b/drivers/block/floppy.c index 09079aee8dc4..398c261fd174 100644 --- a/drivers/block/floppy.c +++ b/drivers/block/floppy.c @@ -3126,7 +3126,8 @@ static int raw_cmd_copyout(int cmd, void __user *param, int ret; while (ptr) { - struct floppy_raw_cmd cmd = *ptr; + struct floppy_raw_cmd cmd; + memcpy(&cmd, ptr, sizeof(cmd)); cmd.next = NULL; cmd.kernel_data = NULL; ret = copy_to_user(param, &cmd, sizeof(cmd)); Thank you, Peilin Ye > 3130 cmd.next = NULL; > 3131 cmd.kernel_data = NULL; > 3132 ret = copy_to_user(param, &cmd, sizeof(cmd)); > ^^^^ > potential info leak. > > 3133 if (ret) > 3134 return -EFAULT; > 3135 param += sizeof(struct floppy_raw_cmd); > 3136 if ((ptr->flags & FD_RAW_READ) && ptr->buffer_length) { > 3137 if (ptr->length >= 0 && > 3138 ptr->length <= ptr->buffer_length) { > 3139 long length = ptr->buffer_length - ptr->length; > 3140 ret = fd_copyout(ptr->data, ptr->kernel_data, > 3141 length); > 3142 if (ret) > 3143 return ret; > 3144 } > 3145 } > 3146 ptr = ptr->next; > 3147 } > 3148 > 3149 return 0; > 3150 } > > regards, > dan carpenter _______________________________________________ Linux-kernel-mentees mailing list Linux-kernel-mentees@lists.linuxfoundation.org https://lists.linuxfoundation.org/mailman/listinfo/linux-kernel-mentees
next prev parent reply other threads:[~2020-07-28 13:13 UTC|newest] Thread overview: 76+ messages / expand[flat|nested] mbox.gz Atom feed top 2020-07-26 16:44 [Linux-kernel-mentees] [PATCH] media/v4l2-core: Fix kernel-infoleak in video_put_user() Peilin Ye 2020-07-26 16:44 ` Peilin Ye 2020-07-26 17:30 ` Laurent Pinchart 2020-07-26 17:30 ` Laurent Pinchart 2020-07-26 18:07 ` Peilin Ye 2020-07-26 18:07 ` Peilin Ye 2020-07-26 22:08 ` Laurent Pinchart 2020-07-26 22:08 ` Laurent Pinchart 2020-07-26 22:15 ` Peilin Ye 2020-07-26 22:15 ` Peilin Ye 2020-07-26 18:12 ` Peilin Ye 2020-07-26 18:12 ` Peilin Ye 2020-07-26 22:05 ` [Linux-kernel-mentees] [PATCH v2] " Peilin Ye 2020-07-26 22:05 ` Peilin Ye 2020-07-26 22:10 ` Laurent Pinchart 2020-07-26 22:10 ` Laurent Pinchart 2020-07-26 22:16 ` Peilin Ye 2020-07-26 22:16 ` Peilin Ye 2020-07-26 22:27 ` [Linux-kernel-mentees] [PATCH v3] " Peilin Ye 2020-07-26 22:27 ` Peilin Ye 2020-07-27 7:25 ` Arnd Bergmann 2020-07-27 7:25 ` Arnd Bergmann 2020-07-27 7:56 ` Peilin Ye 2020-07-27 7:56 ` Peilin Ye 2020-07-27 13:16 ` Dan Carpenter 2020-07-27 13:16 ` Dan Carpenter 2020-07-27 14:05 ` Arnd Bergmann 2020-07-27 14:05 ` Arnd Bergmann 2020-07-27 14:14 ` Peilin Ye 2020-07-27 14:14 ` Peilin Ye 2020-07-27 14:20 ` Arnd Bergmann 2020-07-27 14:20 ` Arnd Bergmann 2020-07-27 14:46 ` Dan Carpenter 2020-07-27 14:46 ` Dan Carpenter 2020-07-27 15:30 ` Peilin Ye 2020-07-27 15:30 ` Peilin Ye 2020-07-27 14:43 ` Dan Carpenter 2020-07-27 14:43 ` Dan Carpenter 2020-07-27 14:55 ` Arnd Bergmann 2020-07-27 14:55 ` Arnd Bergmann 2020-07-27 22:04 ` Peilin Ye 2020-07-27 22:04 ` Peilin Ye 2020-07-28 9:00 ` Arnd Bergmann 2020-07-28 9:00 ` Arnd Bergmann 2020-07-28 10:02 ` Dan Carpenter 2020-07-28 10:02 ` Dan Carpenter 2020-07-27 22:33 ` Peilin Ye 2020-07-27 22:33 ` Peilin Ye 2020-07-28 9:10 ` Arnd Bergmann 2020-07-28 9:10 ` Arnd Bergmann 2020-07-28 9:47 ` Dan Carpenter 2020-07-28 9:47 ` Dan Carpenter 2020-07-28 13:13 ` Peilin Ye [this message] 2020-07-28 13:13 ` Peilin Ye 2020-07-28 12:22 ` Linus Walleij 2020-07-28 12:22 ` Linus Walleij 2020-07-28 13:06 ` Dan Carpenter 2020-07-28 13:06 ` Dan Carpenter 2020-07-28 13:58 ` Arnd Bergmann 2020-07-28 13:58 ` Arnd Bergmann 2020-07-30 8:07 ` Bartosz Golaszewski 2020-07-30 8:07 ` Bartosz Golaszewski 2020-07-30 8:15 ` Arnd Bergmann 2020-07-30 8:15 ` Arnd Bergmann 2020-07-30 8:38 ` Andy Shevchenko 2020-07-30 8:38 ` Andy Shevchenko 2020-07-30 9:18 ` Arnd Bergmann 2020-07-30 9:18 ` Arnd Bergmann 2020-07-30 11:48 ` Andy Shevchenko 2020-07-30 11:48 ` Andy Shevchenko 2020-07-30 13:49 ` Arnd Bergmann 2020-07-30 13:49 ` Arnd Bergmann 2020-08-02 16:55 ` Peilin Ye 2020-08-02 16:55 ` Peilin Ye 2020-07-27 8:00 ` [Linux-kernel-mentees] [PATCH v4] " Peilin Ye 2020-07-27 8:00 ` Peilin Ye
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