From: Ian Abbott Date: Mon, 20 Oct 2014 14:10:40 +0000 (+0100) Subject: staging: comedi: fix memory leak / bad pointer freeing for chanlist X-Git-Tag: omap-for-v3.19/fixes-not-urgent-part1~16^2 X-Git-Url: http://git.openpandora.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=238b5ad855924919e5b98d0c772d9dc78795639b;p=pandora-kernel.git staging: comedi: fix memory leak / bad pointer freeing for chanlist As a follow-up to commit 6cab7a37f5c04 ("staging: comedi: (regression) channel list must be set for COMEDI_CMD ioctl"), Hartley Sweeten pointed out another couple of bugs stemming from commit 6cab7a37f5c04 ("staging: comedi: comedi_fops: introduce __comedi_get_user_chanlist()"). Firstly, `do_cmdtest_ioctl()` never frees the kernel copy of the user chanlist allocated by `__comedi_get_user_chanlist()`, so that memory is leaked. Fix it by freeing the allocated kernel memory pointed to by `cmd.chanlist` before that pointer is overwritten with its original pointer to user memory before `cmd` is copied back to user-space. Secondly, if `__comedi_get_user_chanlist()` returns an error, `cmd->chanlist` is left unchanged and in fact will be a pointer to user memory. This causes `do_cmd_ioctl()` to `goto cleanup` and call `do_become_nonbusy()` which would attempt to free the memory pointed to by the user-space pointer. Fix it by setting `cmd->chanlist` to NULL at the start of `__comedi_get_user_chanlist()`. Fixes: c6cd0eefb27b ("staging: comedi: comedi_fops: introduce __comedi_get_user_chanlist()") Reported-by: H Hartley Sweeten Cc: # 3.15.y 3.16.y 3.17.y: 6cab7a37f5c04 Cc: # 3.15.y 3.16.y 3.17.y Signed-off-by: Greg Kroah-Hartman --- Reading git-diff-tree failed