Patchwork acl: acl_add can't insert before last list element, fix

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Submitter Markus Armbruster
Date June 18, 2013, 8:05 a.m.
Message ID <1371542723-926-1-git-send-email-armbru@redhat.com>
Download mbox | patch
Permalink /patch/252120/
State New
Headers show

Comments

Markus Armbruster - June 18, 2013, 8:05 a.m.
Watch this:

    $ upstream-qemu -nodefaults -S -vnc :0,acl,sasl -monitor stdio
    QEMU 1.5.50 monitor - type 'help' for more information
    (qemu) acl_add vnc.username drei allow
    acl: added rule at position 1
    (qemu) acl_show vnc.username
    policy: deny
    1: allow drei
    (qemu) acl_add vnc.username zwei allow 1
    acl: added rule at position 2
    (qemu) acl_show vnc.username
    policy: deny
    1: allow drei
    2: allow zwei
    (qemu) acl_add vnc.username eins allow 1
    acl: added rule at position 1
    (qemu) acl_show vnc.username
    policy: deny
    1: allow eins
    2: allow drei
    3: allow zwei

The second acl_add inserts at position 2 instead of 1.

Root cause is an off-by-one in qemu_acl_insert(): when index ==
acl->nentries, it appends instead of inserting before the last list
element.

Cc: qemu-stable@nongnu.org
Signed-off-by: Markus Armbruster <armbru@redhat.com>
---
 util/acl.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)
Michael Roth - June 18, 2013, 6:15 p.m.
On Tue, Jun 18, 2013 at 10:05:23AM +0200, Markus Armbruster wrote:
> Watch this:
> 
>     $ upstream-qemu -nodefaults -S -vnc :0,acl,sasl -monitor stdio
>     QEMU 1.5.50 monitor - type 'help' for more information
>     (qemu) acl_add vnc.username drei allow
>     acl: added rule at position 1
>     (qemu) acl_show vnc.username
>     policy: deny
>     1: allow drei
>     (qemu) acl_add vnc.username zwei allow 1
>     acl: added rule at position 2
>     (qemu) acl_show vnc.username
>     policy: deny
>     1: allow drei
>     2: allow zwei
>     (qemu) acl_add vnc.username eins allow 1
>     acl: added rule at position 1
>     (qemu) acl_show vnc.username
>     policy: deny
>     1: allow eins
>     2: allow drei
>     3: allow zwei
> 
> The second acl_add inserts at position 2 instead of 1.
> 
> Root cause is an off-by-one in qemu_acl_insert(): when index ==
> acl->nentries, it appends instead of inserting before the last list
> element.
> 
> Cc: qemu-stable@nongnu.org
> Signed-off-by: Markus Armbruster <armbru@redhat.com>

Reviewed-by: Michael Roth <mdroth@linux.vnet.ibm.com>

> ---
>  util/acl.c | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/util/acl.c b/util/acl.c
> index a7f33ff..938b7ae 100644
> --- a/util/acl.c
> +++ b/util/acl.c
> @@ -138,9 +138,9 @@ int qemu_acl_insert(qemu_acl *acl,
> 
>      if (index <= 0)
>          return -1;
> -    if (index >= acl->nentries)
> +    if (index > acl->nentries) {
>          return qemu_acl_append(acl, deny, match);
> -
> +    }
> 
>      entry = g_malloc(sizeof(*entry));
>      entry->match = g_strdup(match);
> -- 
> 1.7.11.7
> 
>
Michael Tokarev - June 19, 2013, 7:44 a.m.
18.06.2013 12:05, Markus Armbruster wrote:
[]
> The second acl_add inserts at position 2 instead of 1.
> 
> Root cause is an off-by-one in qemu_acl_insert(): when index ==
> acl->nentries, it appends instead of inserting before the last list
> element.

Thanks, applied to the trivial patches queue.

/mjt
Markus Armbruster - July 31, 2013, 2:44 p.m.
Ping re 1.5.3

Markus Armbruster <armbru@redhat.com> writes:

> Watch this:
>
>     $ upstream-qemu -nodefaults -S -vnc :0,acl,sasl -monitor stdio
>     QEMU 1.5.50 monitor - type 'help' for more information
>     (qemu) acl_add vnc.username drei allow
>     acl: added rule at position 1
>     (qemu) acl_show vnc.username
>     policy: deny
>     1: allow drei
>     (qemu) acl_add vnc.username zwei allow 1
>     acl: added rule at position 2
>     (qemu) acl_show vnc.username
>     policy: deny
>     1: allow drei
>     2: allow zwei
>     (qemu) acl_add vnc.username eins allow 1
>     acl: added rule at position 1
>     (qemu) acl_show vnc.username
>     policy: deny
>     1: allow eins
>     2: allow drei
>     3: allow zwei
>
> The second acl_add inserts at position 2 instead of 1.
>
> Root cause is an off-by-one in qemu_acl_insert(): when index ==
> acl->nentries, it appends instead of inserting before the last list
> element.
>
> Cc: qemu-stable@nongnu.org
> Signed-off-by: Markus Armbruster <armbru@redhat.com>
> ---
>  util/acl.c | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
>
> diff --git a/util/acl.c b/util/acl.c
> index a7f33ff..938b7ae 100644
> --- a/util/acl.c
> +++ b/util/acl.c
> @@ -138,9 +138,9 @@ int qemu_acl_insert(qemu_acl *acl,
>  
>      if (index <= 0)
>          return -1;
> -    if (index >= acl->nentries)
> +    if (index > acl->nentries) {
>          return qemu_acl_append(acl, deny, match);
> -
> +    }
>  
>      entry = g_malloc(sizeof(*entry));
>      entry->match = g_strdup(match);

Patch

diff --git a/util/acl.c b/util/acl.c
index a7f33ff..938b7ae 100644
--- a/util/acl.c
+++ b/util/acl.c
@@ -138,9 +138,9 @@  int qemu_acl_insert(qemu_acl *acl,
 
     if (index <= 0)
         return -1;
-    if (index >= acl->nentries)
+    if (index > acl->nentries) {
         return qemu_acl_append(acl, deny, match);
-
+    }
 
     entry = g_malloc(sizeof(*entry));
     entry->match = g_strdup(match);