2012-11-14 11:50:00

by Colin King

Subject: [PATCH RESEND] pstore: fix NULL pointer dereference in console writes

From: Colin Ian King <[email protected]>

Passing a NULL id causes a NULL pointer deference in writers
such as erst_writer and efi_pstore_write because they expect
to update this id. Pass a dummy id instead.

This avoids a cascade of oopses caused when the initial
pstore_console_write passes a null which in turn causes
writes to the console causing further oopses in subsequent
pstore_console_write calls.

Signed-off-by: Colin Ian King <[email protected]>
Acked-by: Kees Cook <[email protected]>
---
fs/pstore/platform.c | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/fs/pstore/platform.c b/fs/pstore/platform.c
index a40da07..947fbe0 100644
--- a/fs/pstore/platform.c
+++ b/fs/pstore/platform.c
@@ -161,6 +161,7 @@ static void pstore_console_write(struct console *con, const char *s, unsigned c)

while (s < e) {
unsigned long flags;
+ u64 id;

if (c > psinfo->bufsize)
c = psinfo->bufsize;
@@ -172,7 +173,7 @@ static void pstore_console_write(struct console *con, const char *s, unsigned c)
spin_lock_irqsave(&psinfo->buf_lock, flags);
}
memcpy(psinfo->buf, s, c);
- psinfo->write(PSTORE_TYPE_CONSOLE, 0, NULL, 0, c, psinfo);
+ psinfo->write(PSTORE_TYPE_CONSOLE, 0, &id, 0, c, psinfo);
spin_unlock_irqrestore(&psinfo->buf_lock, flags);
s += c;
c = e - s;
--
1.7.10.4

2012-11-15 02:53:14

by Anton Vorontsov

Subject: Re: [PATCH RESEND] pstore: fix NULL pointer dereference in console writes

On Wed, Nov 14, 2012 at 11:49:53AM +0000, Colin King wrote:
> From: Colin Ian King <[email protected]>
>
> Passing a NULL id causes a NULL pointer deference in writers
> such as erst_writer and efi_pstore_write because they expect
> to update this id. Pass a dummy id instead.
>
> This avoids a cascade of oopses caused when the initial
> pstore_console_write passes a null which in turn causes
> writes to the console causing further oopses in subsequent
> pstore_console_write calls.
>
> Signed-off-by: Colin Ian King <[email protected]>
> Acked-by: Kees Cook <[email protected]>
> ---

Ugh. Thanks for the reminder, I completely forgot that I had this bit for
v3.7.

Applied, thanks! (I also added Cc: stable.)

> fs/pstore/platform.c | 3 ++-
> 1 file changed, 2 insertions(+), 1 deletion(-)
>
> diff --git a/fs/pstore/platform.c b/fs/pstore/platform.c
> index a40da07..947fbe0 100644
> --- a/fs/pstore/platform.c
> +++ b/fs/pstore/platform.c
> @@ -161,6 +161,7 @@ static void pstore_console_write(struct console *con, const char *s, unsigned c)
>
> while (s < e) {
> unsigned long flags;
> + u64 id;
>
> if (c > psinfo->bufsize)
> c = psinfo->bufsize;
> @@ -172,7 +173,7 @@ static void pstore_console_write(struct console *con, const char *s, unsigned c)
> spin_lock_irqsave(&psinfo->buf_lock, flags);
> }
> memcpy(psinfo->buf, s, c);
> - psinfo->write(PSTORE_TYPE_CONSOLE, 0, NULL, 0, c, psinfo);
> + psinfo->write(PSTORE_TYPE_CONSOLE, 0, &id, 0, c, psinfo);
> spin_unlock_irqrestore(&psinfo->buf_lock, flags);
> s += c;
> c = e - s;
> --
> 1.7.10.4