On Mon, Feb 10, 2025 at 12:54 AM Chris Moore via
lists.yoctoproject.org
<cmoore=hanoverdisplays....@lists.yoctoproject.org> wrote:
>
> From: Chris Moore <cmo...@hanoverdisplays.com>
> Date: Fri, 7 Feb 2025 15:21:02 +0000
> Subject: [psplash][PATCH] psplash.c: fix crash from length becoming
> negative
>
> Fixes [Yocto #14806]
>
> If there is an error in read(), it returns -1 but this is just added to
> length without checking first. This can lead to a runaway negative
> value
> for length which eventually crashes when memchr() is called with the
> negative value.
>
> The fix is to check the return from read() first and handle the error
> state.
>
> Signed-off-by: Chris Moore <cmo...@hanoverdisplays.com>
> ---
> psplash.c | 6 ++++--
> 1 file changed, 4 insertions(+), 2 deletions(-)
>
> diff --git a/psplash.c b/psplash.c
> index ee1af6b..0db0aa4 100644
> --- a/psplash.c
> +++ b/psplash.c
> @@ -140,6 +140,7 @@ psplash_main (PSplashFB *fb, int pipe_fd, int
> timeout)
> {
> int err;
> ssize_t length = 0;
> + ssize_t ret = 0;
> fd_set descriptors;
> struct timeval tv;
> char *end;
> @@ -170,15 +171,16 @@ psplash_main (PSplashFB *fb, int pipe_fd, int
> timeout)
> return;
> }
>
> - length += read (pipe_fd, end, sizeof(command) - (end -
> command));
> + ret = read (pipe_fd, end, sizeof(command) - (end - command));
good find. even -Wunused-result would not catch it :)
>
> - if (length == 0)
> + if (ret <= 0)
> {
> /* Reopen to see if there's anything more for us */
> close(pipe_fd);
> pipe_fd = open(PSPLASH_FIFO,O_RDONLY|O_NONBLOCK);
> goto out;
> }
> + length += ret;
>
> cmd = command;
> do {
> --
> 2.45.2
>
>
> Chris Moore
>
>
> Embedded Software Engineer
>
>
>
>
>
> @ cmo...@hanoverdisplays.com
> T +44 1273 477528
>
>
> www.hanoverdisplays.comHanover Displays Ltd. Southerham House, Southerham
> Lane, Lewes, East Sussex BN8 6JN, UK
>
>
> Registered in England No: 1876684
>
>
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