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| author | Thomas Weißschuh <linux@weissschuh.net> | 2023-02-20 06:46:12 +0000 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2023-03-03 11:52:23 +0100 |
| commit | a595a81df673c69b9d2cb31f7b2ad8fdcf402d2d (patch) | |
| tree | b0ad9a00f47b2d0fe046b2e2314325c0447393d4 | |
| parent | ea4c208efea491be93e37a85b1acd973dbe8594f (diff) | |
| download | linux-a595a81df673c69b9d2cb31f7b2ad8fdcf402d2d.tar.gz | |
vc_screen: don't clobber return value in vcs_read
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>
| -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 f566eb1839dc..71e091f879f0 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 |