On Mon, Apr 22, 2024 at 04:51:49PM -0700, Doug Anderson wrote:
Hi,
On Mon, Apr 22, 2024 at 9:37 AM Daniel Thompson daniel.thompson@linaro.org wrote:
Currently, when the user attempts symbol completion with the Tab key, kdb will use strncpy() to insert the completed symbol into the command buffer. Unfortunately it passes the size of the source buffer rather than the destination to strncpy() with predictably horrible results. Most obviously if the command buffer is already full but cp, the cursor position, is in the middle of the buffer, then we will write past the end of the supplied buffer.
Fix this by replacing the dubious strncpy() calls with memmove()/memcpy() calls plus explicit boundary checks to make sure we have enough space before we start moving characters around.
Reported-by: Justin Stitt justinstitt@google.com Closes: https://lore.kernel.org/all/CAFhGd8qESuuifuHsNjFPR-Va3P80bxrw+LqvC8deA8GziUJ... Cc: stable@vger.kernel.org Signed-off-by: Daniel Thompson daniel.thompson@linaro.org
kernel/debug/kdb/kdb_io.c | 21 +++++++++++++-------- 1 file changed, 13 insertions(+), 8 deletions(-)
Boy, this function (and especially the tab handling) is hard to read.
Too right. I even rewrote it using offsets rather than pointers at one point (it didn't really make it much clearer so I dropped that for now).
I spent a bit of time trying to grok it and, as far as I can tell, your patch makes things better and I don't see any bugs.
Reviewed-by: Douglas Anderson dianders@chromium.org
Thanks!
Daniel.