Messages in this thread | | | Date | Mon, 20 Feb 2023 12:48:59 +0100 | Subject | Re: [PATCH] vc_screen: don't clobber return value in vcs_read | From | Jiri Slaby <> |
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On 20. 02. 23, 7:46, linux@weissschuh.net wrote: > From: Thomas Weißschuh <linux@weissschuh.net> > > 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.
Not sure -- I cannot find it -- but hasn't George fixed this yet?
> 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> > > --- > > @Storm Could you validate this patch? > --- > drivers/tty/vt/vc_screen.c | 5 +++-- > 1 file changed, 3 insertions(+), 2 deletions(-) > > diff --git a/drivers/tty/vt/vc_screen.c b/drivers/tty/vt/vc_screen.c > index f566eb1839dc..2ef519a40a87 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) > + if (!vc) { > + ret = -ENXIO; > goto unlock_out; > + } > > /* Check whether we are above size each round, > * as copy_to_user at the end of this loop > > base-commit: c9c3395d5e3dcc6daee66c6908354d47bf98cb0c
-- js suse labs
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