sent

my build of simple presentation viewer
git clone git://git.kocotian.pl/sent.git
Log | Files | Refs | README | LICENSE

commit 2649e8d5334f7e37a1710c60fb740ecfe91b9f9e
parent 72d33d463fed7ba271961a6f91cae1fed8faa454
Author: Chris Down <chris@chrisdown.name>
Date:   Wed, 13 May 2020 12:20:53 +0100

Avoid out-of-bounds access when a slide input line begins with \0

If we read in a line with \0 at the beginning, blen will be 0. However,
we then try to index our copy of the buffer with
s->lines[s->linecount][blen-1], we'll read (and potentially write if the
data happens to be 0x0A) outside of strdup's allocated memory, and may
crash.

Fix this by just rejecting lines with a leading \0. Lines with nulls
embedded in other places don't invoke similar behaviour, since the
length is still >0.

Diffstat:
Msent.c | 4++++
1 file changed, 4 insertions(+), 0 deletions(-)

diff --git a/sent.c b/sent.c @@ -428,6 +428,10 @@ load(FILE *fp) maxlines = 0; memset((s = &slides[slidecount]), 0, sizeof(Slide)); do { + /* if there's a leading null, we can't do blen-1 */ + if (buf[0] == '\0') + continue; + if (buf[0] == '#') continue;