From: Thomas Weißschuh <linux@weissschuh.net> 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=... -------------------------------- 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 <stormdragon2976@gmail.com> 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 <linux@weissschuh.net> Link: https://lore.kernel.org/lkml/64981d94-d00c-4b31-9063-43ad0a384bde@t-8ch.de/ Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Signed-off-by: Yi Yang <yiyang13@huawei.com> --- 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 -- 2.25.1