Messages in this thread Patch in this message | | | From | Sukrut Bellary <> | Subject | [PATCH] misc: fastrpc: Fix double free of 'buf' in error path | Date | Thu, 18 May 2023 03:08:29 -0700 |
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smatch warning: drivers/misc/fastrpc.c:1926 fastrpc_req_mmap() error: double free of 'buf'
In fastrpc_req_mmap() error path, the fastrpc buffer is freed in fastrpc_req_munmap_impl() if unmap is successful.
But in the end, there is an unconditional call to fastrpc_buf_free(). So the above case triggers the double free of fastrpc buf.
Fix this by avoiding the call to the second fastrpc_buf_free() if fastrpc_req_munmap_impl() is successful. 'err' is not updated as it needs to retain the err returned by qcom_scm_assign_mem(), which is the starting point of this error path.
This is based on static analysis only. Compilation tested.
Reviewed-by: Shuah Khan <skhan@linuxfoundation.org> Signed-off-by: Sukrut Bellary <sukrut.bellary@linux.com> --- drivers/misc/fastrpc.c | 5 ++++- 1 file changed, 4 insertions(+), 1 deletion(-)
diff --git a/drivers/misc/fastrpc.c b/drivers/misc/fastrpc.c index f48466960f1b..1c3ab78f274f 100644 --- a/drivers/misc/fastrpc.c +++ b/drivers/misc/fastrpc.c @@ -1921,7 +1921,10 @@ static int fastrpc_req_mmap(struct fastrpc_user *fl, char __user *argp) return 0; err_assign: - fastrpc_req_munmap_impl(fl, buf); + if (!fastrpc_req_munmap_impl(fl, buf)) { + /* buf is freed */ + return err; + } err_invoke: fastrpc_buf_free(buf); -- 2.34.1
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