3.12-stable review patch. If anyone has any objections, please let me know.
------------------ From: Peter Hurley <[email protected]> commit c77569d2f3ef7844ee4ac7005a57da6898b302a8 upstream. Although the maximum allowable canonical line is specified to be 255 bytes (MAX_CANON), the practical limit has actually been the size of the line discipline read buffer (N_TTY_BUF_SIZE == 4096). Commit 32f13521ca68bc624ff6effc77f308a52b038bf0, n_tty: Line copy to user buffer in canonical mode, limited the line copy to 4095 bytes. With a completely full line discipline read buffer and a userspace buffer > 4095, _no_ data was copied, and the read() syscall returned 0, indicating EOF. Fix the interval arithmetic to compute the correct number of bytes to copy to userspace in the range [1..4096]. Signed-off-by: Peter Hurley <[email protected]> Signed-off-by: Greg Kroah-Hartman <[email protected]> --- drivers/tty/n_tty.c | 5 ++++- 1 file changed, 4 insertions(+), 1 deletion(-) --- a/drivers/tty/n_tty.c +++ b/drivers/tty/n_tty.c @@ -2005,7 +2005,10 @@ static int canon_copy_from_read_buf(stru found = 1; size = N_TTY_BUF_SIZE - tail; - n = (found + eol + size) & (N_TTY_BUF_SIZE - 1); + n = eol - tail; + if (n > 4096) + n += 4096; + n += found; c = n; if (found && read_buf(ldata, eol) == __DISABLED_CHAR) { -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
