From bc26957c6cd913eaec9aac4ce17953efc1582c2e Mon Sep 17 00:00:00 2001 From: Julia Lawall Date: Sun, 21 Oct 2012 00:52:05 +0000 Subject: [PATCH] powerpc/rtas_flash: Eliminate possible double free The function initialize_flash_pde_data is only called four times. All four calls are in the function rtas_flash_init, and on the failure of any of the calls, remove_flash_pde is called on the third argument of each of the calls. There is thus no need for initialize_flash_pde_data to call remove_flash_pde on the same argument. remove_flash_pde kfrees the data field of its argument, and does not clear that field, so this amounts ot a possible double free. A simplified version of the semantic match that finds this problem is as follows: (http://coccinelle.lip6.fr/) // @r@ identifier f,free,a; parameter list[n] ps; type T; expression e; @@ f(ps,T a,...) { ... when any when != a = e if(...) { ... free(a); ... return ...; } ... when any } @@ identifier r.f,r.free; expression x,a; expression list[r.n] xs; @@ * x = f(xs,a,...); if (...) { ... free(a); ... return ...; } // Signed-off-by: Julia Lawall Signed-off-by: Benjamin Herrenschmidt --- arch/powerpc/kernel/rtas_flash.c | 4 +--- 1 file changed, 1 insertion(+), 3 deletions(-) diff --git a/arch/powerpc/kernel/rtas_flash.c b/arch/powerpc/kernel/rtas_flash.c index 20b0120db0c3..8329190312c1 100644 --- a/arch/powerpc/kernel/rtas_flash.c +++ b/arch/powerpc/kernel/rtas_flash.c @@ -650,10 +650,8 @@ static int initialize_flash_pde_data(const char *rtas_call_name, int token; dp->data = kzalloc(buf_size, GFP_KERNEL); - if (dp->data == NULL) { - remove_flash_pde(dp); + if (dp->data == NULL) return -ENOMEM; - } /* * This code assumes that the status int is the first member of the -- 2.20.1