From 87baad7512d16d0d48a0b359c1281d0ee7ea2312 Mon Sep 17 00:00:00 2001 From: George Kennedy Date: Thu, 10 Apr 2025 03:09:38 +0000 Subject: [PATCH 1/3] vc_screen: move load of struct vc_data pointer in vcs_read() to avoid UAF stable inclusion from stable-v4.19.273 commit 6332f52f44b9776568bf3c0b714ddfb0bb175e78 category: bugfix bugzilla: https://gitee.com/src-openeuler/kernel/issues/IBWVWQ CVE: CVE-2023-52973 Reference: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=6332f52f44b9776568bf3c0b714ddfb0bb175e78 -------------------------------- [ Upstream commit 226fae124b2dac217ea5436060d623ff3385bc34 ] After a call to console_unlock() in vcs_read() the vc_data struct can be freed by vc_deallocate(). Because of that, the struct vc_data pointer load must be done at the top of while loop in vcs_read() to avoid a UAF when vcs_size() is called. Syzkaller reported a UAF in vcs_size(). BUG: KASAN: use-after-free in vcs_size (drivers/tty/vt/vc_screen.c:215) Read of size 4 at addr ffff8881137479a8 by task 4a005ed81e27e65/1537 CPU: 0 PID: 1537 Comm: 4a005ed81e27e65 Not tainted 6.2.0-rc5 #1 Hardware name: Red Hat KVM, BIOS 1.15.0-2.module Call Trace: __asan_report_load4_noabort (mm/kasan/report_generic.c:350) vcs_size (drivers/tty/vt/vc_screen.c:215) vcs_read (drivers/tty/vt/vc_screen.c:415) vfs_read (fs/read_write.c:468 fs/read_write.c:450) ... Allocated by task 1191: ... kmalloc_trace (mm/slab_common.c:1069) vc_allocate (./include/linux/slab.h:580 ./include/linux/slab.h:720 drivers/tty/vt/vt.c:1128 drivers/tty/vt/vt.c:1108) con_install (drivers/tty/vt/vt.c:3383) tty_init_dev (drivers/tty/tty_io.c:1301 drivers/tty/tty_io.c:1413 drivers/tty/tty_io.c:1390) tty_open (drivers/tty/tty_io.c:2080 drivers/tty/tty_io.c:2126) chrdev_open (fs/char_dev.c:415) do_dentry_open (fs/open.c:883) vfs_open (fs/open.c:1014) ... Freed by task 1548: ... kfree (mm/slab_common.c:1021) vc_port_destruct (drivers/tty/vt/vt.c:1094) tty_port_destructor (drivers/tty/tty_port.c:296) tty_port_put (drivers/tty/tty_port.c:312) vt_disallocate_all (drivers/tty/vt/vt_ioctl.c:662 (discriminator 2)) vt_ioctl (drivers/tty/vt/vt_ioctl.c:903) tty_ioctl (drivers/tty/tty_io.c:2776) ... The buggy address belongs to the object at ffff888113747800 which belongs to the cache kmalloc-1k of size 1024 The buggy address is located 424 bytes inside of 1024-byte region [ffff888113747800, ffff888113747c00) The buggy address belongs to the physical page: page:00000000b3fe6c7c refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x113740 head:00000000b3fe6c7c order:3 compound_mapcount:0 subpages_mapcount:0 compound_pincount:0 anon flags: 0x17ffffc0010200(slab|head|node=0|zone=2|lastcpupid=0x1fffff) raw: 0017ffffc0010200 ffff888100042dc0 0000000000000000 dead000000000001 raw: 0000000000000000 0000000000100010 00000001ffffffff 0000000000000000 page dumped because: kasan: bad access detected Memory state around the buggy address: ffff888113747880: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ffff888113747900: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb > ffff888113747980: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ^ ffff888113747a00: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ffff888113747a80: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ================================================================== Disabling lock debugging due to kernel taint Fixes: ac751efa6a0d ("console: rename acquire/release_console_sem() to console_lock/unlock()") Reported-by: syzkaller Suggested-by: Jiri Slaby Signed-off-by: George Kennedy Link: https://lore.kernel.org/r/1674577014-12374-1-git-send-email-george.kennedy@oracle.com Signed-off-by: Greg Kroah-Hartman Signed-off-by: Sasha Levin Signed-off-by: Yi Yang --- drivers/tty/vt/vc_screen.c | 9 +++++---- 1 file changed, 5 insertions(+), 4 deletions(-) diff --git a/drivers/tty/vt/vc_screen.c b/drivers/tty/vt/vc_screen.c index 2fb509d57e88..03fe692d940b 100644 --- a/drivers/tty/vt/vc_screen.c +++ b/drivers/tty/vt/vc_screen.c @@ -247,10 +247,6 @@ vcs_read(struct file *file, char __user *buf, size_t count, loff_t *ppos) uni_mode = use_unicode(inode); attr = use_attributes(inode); - ret = -ENXIO; - vc = vcs_vc(inode, &viewed); - if (!vc) - goto unlock_out; ret = -EINVAL; if (pos < 0) @@ -270,6 +266,11 @@ vcs_read(struct file *file, char __user *buf, size_t count, loff_t *ppos) ssize_t orig_count; long p = pos; + ret = -ENXIO; + vc = vcs_vc(inode, &viewed); + if (!vc) + goto unlock_out; + /* Check whether we are above size each round, * as copy_to_user at the end of this loop * could sleep. -- Gitee From 5f5619a7cc8350619d44443e00d6082274da7398 Mon Sep 17 00:00:00 2001 From: George Kennedy Date: Thu, 10 Apr 2025 03:09:39 +0000 Subject: [PATCH 2/3] vc_screen: modify vcs_size() handling in vcs_read() stable inclusion from stable-v4.19.276 commit 61a96ad27addecaba100213c7089bf2ebd20c6e4 category: bugfix bugzilla: https://gitee.com/src-openeuler/kernel/issues/IBWVWQ CVE: CVE-2023-52973 Reference: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=61a96ad27addecaba100213c7089bf2ebd20c6e4 -------------------------------- [ Upstream commit 46d733d0efc79bc8430d63b57ab88011806d5180 ] Restore the vcs_size() handling in vcs_read() to what it had been in previous version. Fixes: 226fae124b2d ("vc_screen: move load of struct vc_data pointer in vcs_read() to avoid UAF") Suggested-by: Jiri Slaby Signed-off-by: George Kennedy Signed-off-by: Linus Torvalds Signed-off-by: Sasha Levin Signed-off-by: Yi Yang --- drivers/tty/vt/vc_screen.c | 4 +--- 1 file changed, 1 insertion(+), 3 deletions(-) diff --git a/drivers/tty/vt/vc_screen.c b/drivers/tty/vt/vc_screen.c index 03fe692d940b..6b573d130ea9 100644 --- a/drivers/tty/vt/vc_screen.c +++ b/drivers/tty/vt/vc_screen.c @@ -277,10 +277,8 @@ vcs_read(struct file *file, char __user *buf, size_t count, loff_t *ppos) */ size = vcs_size(inode); if (size < 0) { - if (read) - break; ret = size; - goto unlock_out; + break; } if (pos >= size) break; -- Gitee From cbc7fa2e081e72708e48aba8292d3aa361349758 Mon Sep 17 00:00:00 2001 From: =?UTF-8?q?Thomas=20Wei=C3=9Fschuh?= Date: Thu, 10 Apr 2025 03:09:40 +0000 Subject: [PATCH 3/3] vc_screen: don't clobber return value in vcs_read MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit stable inclusion from stable-v4.19.275 commit e534b1ce31679ad447aa07690b5c327c767a6020 category: bugfix bugzilla: https://gitee.com/src-openeuler/kernel/issues/IBWVWQ CVE: CVE-2023-52973 Reference: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=e534b1ce31679ad447aa07690b5c327c767a6020 -------------------------------- commit ae3419fbac845b4d3f3a9fae4cc80c68d82cdf6e upstream. Commit 226fae124b2d ("vc_screen: move load of struct vc_data pointer in vcs_read() to avoid UAF") moved the call to vcs_vc() into the loop. While doing this it also moved the unconditional assignment of ret = -ENXIO; This unconditional assignment was valid outside the loop but within it it clobbers the actual value of ret. To avoid this only assign "ret = -ENXIO" when actually needed. [ Also, the 'goto unlock_out" needs to be just a "break", so that it does the right thing when it exits on later iterations when partial success has happened - Linus ] Reported-by: Storm Dragon Link: https://lore.kernel.org/lkml/Y%2FKS6vdql2pIsCiI@hotmail.com/ Fixes: 226fae124b2d ("vc_screen: move load of struct vc_data pointer in vcs_read() to avoid UAF") Signed-off-by: Thomas Weißschuh Link: https://lore.kernel.org/lkml/64981d94-d00c-4b31-9063-43ad0a384bde@t-8ch.de/ Signed-off-by: Linus Torvalds Signed-off-by: Greg Kroah-Hartman Signed-off-by: Yi Yang --- drivers/tty/vt/vc_screen.c | 7 ++++--- 1 file changed, 4 insertions(+), 3 deletions(-) diff --git a/drivers/tty/vt/vc_screen.c b/drivers/tty/vt/vc_screen.c index 6b573d130ea9..28bc9c70de3e 100644 --- a/drivers/tty/vt/vc_screen.c +++ b/drivers/tty/vt/vc_screen.c @@ -266,10 +266,11 @@ vcs_read(struct file *file, char __user *buf, size_t count, loff_t *ppos) ssize_t orig_count; long p = pos; - ret = -ENXIO; vc = vcs_vc(inode, &viewed); - if (!vc) - goto unlock_out; + if (!vc) { + ret = -ENXIO; + break; + } /* Check whether we are above size each round, * as copy_to_user at the end of this loop -- Gitee