The Coverity output is:
*** CID 366905: Memory - illegal accesses (USE_AFTER_FREE)
/grub-core/disk/cryptodisk.c: 1064 in grub_cryptodisk_scan_device_real()
1058 cleanup:
1059 if (askpass)
1060 {
1061 cargs->key_len = 0;
1062 grub_free (cargs->key_data);
1063 }
>>> CID 366905: Memory - illegal accesses (USE_AFTER_FREE)
>>> Using freed pointer "dev".
1064 return dev;
1065 }
1066
1067 #ifdef GRUB_UTIL
1068 #include <grub/util/misc.h>
1069 grub_err_t
Here the 'dev' variable can point to a freed cryptodisk device if the
function grub_cryptodisk_insert() fails. This can happen only on a OOM
condition, but when this happens grub_cryptodisk_insert() calls grub_free on
the passed device. Since grub_cryptodisk_scan_device_real() assumes that
grub_cryptodisk_insert() is always successful, it will return the device,
though the device was freed.
Change grub_cryptodisk_insert() to not free the passed device on failure.
Then on grub_cryptodisk_insert() failure, free the device pointer. This is
done by going to the label 'error', which will call cryptodisk_close() to
free the device and set the device pointer to NULL, so that a pointer to
freed memory is not returned.
Signed-off-by: Glenn Washburn <developm...@efficientek.com>
---
Having reviewed the Coverity error, I believe this is the fix needed to resolve
the use after free reported by Coverity. However, I do not currently have
Coverity setup, so I don't have a way to test if this is both necessary and
sufficient to resolve the Coverity error. Regardess, I do believe that is does
fix a real use after free bug.
Glenn
---
grub-core/disk/cryptodisk.c | 9 ++++-----
1 file changed, 4 insertions(+), 5 deletions(-)
diff --git a/grub-core/disk/cryptodisk.c b/grub-core/disk/cryptodisk.c
index 497097394..e7c4795fd 100644
--- a/grub-core/disk/cryptodisk.c
+++ b/grub-core/disk/cryptodisk.c
@@ -889,10 +889,7 @@ grub_cryptodisk_insert (grub_cryptodisk_t newdev, const
char *name,
{
newdev->source = grub_strdup (name);
if (!newdev->source)
- {
- grub_free (newdev);
- return grub_errno;
- }
+ return grub_errno;
newdev->id = last_cryptodisk_id++;
newdev->source_id = source->id;
@@ -1044,7 +1041,9 @@ grub_cryptodisk_scan_device_real (const char *name,
if (ret != GRUB_ERR_NONE)
goto error;
- grub_cryptodisk_insert (dev, name, source);
+ ret = grub_cryptodisk_insert (dev, name, source);
+ if (ret != GRUB_ERR_NONE)
+ goto error;
goto cleanup;
}
--
2.27.0
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