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Re: [Qemu-devel] [PATCH v2] bsd_user: Fix potential null pointer derefer


From: Stefan Weil
Subject: Re: [Qemu-devel] [PATCH v2] bsd_user: Fix potential null pointer dereference
Date: Mon, 28 Nov 2011 18:55:43 +0100
User-agent: Mozilla/5.0 (X11; U; Linux x86_64; en-US; rv:1.9.1.16) Gecko/20111110 Iceowl/1.0b1 Icedove/3.0.11

Am 21.11.2011 21:06, schrieb Stefan Weil:
This bug was spotted by cppcheck.

Using g_try_malloc0 (as does the linux-user code) fixes this.

v2:
Use g_free in bsdload.c, too. Thanks to Peter Maydell for this hint.

Signed-off-by: Stefan Weil<address@hidden>
---
  bsd-user/bsdload.c |    2 +-
  bsd-user/elfload.c |    5 ++---
  2 files changed, 3 insertions(+), 4 deletions(-)

diff --git a/bsd-user/bsdload.c b/bsd-user/bsdload.c
index 6d9bb6f..2abc713 100644
--- a/bsd-user/bsdload.c
+++ b/bsd-user/bsdload.c
@@ -196,7 +196,7 @@ int loader_exec(const char * filename, char ** argv, char 
** envp,

      /* Something went wrong, return the inode and free the argument pages*/
      for (i=0 ; i<MAX_ARG_PAGES ; i++) {
-        free(bprm.page[i]);
+        g_free(bprm.page[i]);
      }
      return(retval);
  }
diff --git a/bsd-user/elfload.c b/bsd-user/elfload.c
index 1ef1f97..1288884 100644
--- a/bsd-user/elfload.c
+++ b/bsd-user/elfload.c
@@ -641,8 +641,7 @@ static abi_ulong copy_elf_strings(int argc,char ** argv, 
void **page,
                  offset = p % TARGET_PAGE_SIZE;
                  pag = (char *)page[p/TARGET_PAGE_SIZE];
                  if (!pag) {
-                    pag = (char *)malloc(TARGET_PAGE_SIZE);
-                    memset(pag, 0, TARGET_PAGE_SIZE);
+                    pag = g_try_malloc0(TARGET_PAGE_SIZE);
                      page[p/TARGET_PAGE_SIZE] = pag;
                      if (!pag)
                          return 0;
@@ -696,7 +695,7 @@ static abi_ulong setup_arg_pages(abi_ulong p, struct 
linux_binprm *bprm,
              info->rss++;
              /* FIXME - check return value of memcpy_to_target() for failure */
              memcpy_to_target(stack_base, bprm->page[i], TARGET_PAGE_SIZE);
-            free(bprm->page[i]);
+            g_free(bprm->page[i]);
          }
          stack_base += TARGET_PAGE_SIZE;
      }

Ping? Can this be fixed in QEMU 1.0?




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