Wenwen Wang
2019-Jul-20 12:22 UTC
[Bridge] [PATCH] netfilter: ebtables: compat: fix a memory leak bug
From: Wenwen Wang <wenwen at cs.uga.edu> In compat_do_replace(), a temporary buffer is allocated through vmalloc() to hold entries copied from the user space. The buffer address is firstly saved to 'newinfo->entries', and later on assigned to 'entries_tmp'. Then the entries in this temporary buffer is copied to the internal kernel structure through compat_copy_entries(). If this copy process fails, compat_do_replace() should be terminated. However, the allocated temporary buffer is not freed on this path, leading to a memory leak. To fix the bug, free the buffer before returning from compat_do_replace(). Signed-off-by: Wenwen Wang <wenwen at cs.uga.edu> --- net/bridge/netfilter/ebtables.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-) diff --git a/net/bridge/netfilter/ebtables.c b/net/bridge/netfilter/ebtables.c index 963dfdc..fd84b48e 100644 --- a/net/bridge/netfilter/ebtables.c +++ b/net/bridge/netfilter/ebtables.c @@ -2261,8 +2261,10 @@ static int compat_do_replace(struct net *net, void __user *user, state.buf_kern_len = size64; ret = compat_copy_entries(entries_tmp, tmp.entries_size, &state); - if (WARN_ON(ret < 0)) + if (WARN_ON(ret < 0)) { + vfree(entries_tmp); goto out_unlock; + } vfree(entries_tmp); tmp.entries_size = size64; -- 2.7.4
Florian Westphal
2019-Jul-21 00:26 UTC
[Bridge] [PATCH] netfilter: ebtables: compat: fix a memory leak bug
Wenwen Wang <wang6495 at umn.edu> wrote:> From: Wenwen Wang <wenwen at cs.uga.edu> > > In compat_do_replace(), a temporary buffer is allocated through vmalloc() > to hold entries copied from the user space. The buffer address is firstly > saved to 'newinfo->entries', and later on assigned to 'entries_tmp'. Then > the entries in this temporary buffer is copied to the internal kernel > structure through compat_copy_entries(). If this copy process fails, > compat_do_replace() should be terminated. However, the allocated temporary > buffer is not freed on this path, leading to a memory leak. > > To fix the bug, free the buffer before returning from compat_do_replace(). > > Signed-off-by: Wenwen Wang <wenwen at cs.uga.edu>Reviewed-by: Florian Westphal <fw at strlen.de>
Pablo Neira Ayuso
2019-Jul-21 18:59 UTC
[Bridge] [PATCH] netfilter: ebtables: compat: fix a memory leak bug
On Sat, Jul 20, 2019 at 07:22:45AM -0500, Wenwen Wang wrote:> From: Wenwen Wang <wenwen at cs.uga.edu> > > In compat_do_replace(), a temporary buffer is allocated through vmalloc() > to hold entries copied from the user space. The buffer address is firstly > saved to 'newinfo->entries', and later on assigned to 'entries_tmp'. Then > the entries in this temporary buffer is copied to the internal kernel > structure through compat_copy_entries(). If this copy process fails, > compat_do_replace() should be terminated. However, the allocated temporary > buffer is not freed on this path, leading to a memory leak. > > To fix the bug, free the buffer before returning from compat_do_replace().Applied, thanks.