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| author | Thomas Weißschuh <linux@weissschuh.net> | 2023-02-20 06:46:12 +0000 |
|---|---|---|
| committer | Linus Torvalds <torvalds@linux-foundation.org> | 2023-02-27 18:35:28 -0800 |
| commit | ae3419fbac845b4d3f3a9fae4cc80c68d82cdf6e (patch) | |
| tree | c6be34e2933c06ce4ae1a972be5ff25f4600644f /drivers | |
| parent | 981ee95cc1f5905ae4936b0dd501085909cdc14f (diff) | |
| download | lwn-ae3419fbac845b4d3f3a9fae4cc80c68d82cdf6e.tar.gz lwn-ae3419fbac845b4d3f3a9fae4cc80c68d82cdf6e.zip | |
vc_screen: don't clobber return value in vcs_read
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>
Diffstat (limited to 'drivers')
| -rw-r--r-- | drivers/tty/vt/vc_screen.c | 7 |
1 files changed, 4 insertions, 3 deletions
diff --git a/drivers/tty/vt/vc_screen.c b/drivers/tty/vt/vc_screen.c index c0a2273bb998..1dc07f9214d5 100644 --- a/drivers/tty/vt/vc_screen.c +++ b/drivers/tty/vt/vc_screen.c @@ -403,10 +403,11 @@ vcs_read(struct file *file, char __user *buf, size_t count, loff_t *ppos) unsigned int this_round, skip = 0; int size; - 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 |