[PATCH v2] cxgb3i: fix ddp map overrun (version 2)

From: Karen Xie <k...@chelsio.com>

Fixed a bug in calculating ddp map range when search for free entries:
it was going beyond the end by one, thus corrupting gl_skb[0].

Signed-off-by: Karen Xie <k...@chelsio.com>
---

 drivers/scsi/cxgb3i/cxgb3i_ddp.c |   32 +++++++++++++++++++-------------
 1 files changed, 19 insertions(+), 13 deletions(-)


diff --git a/drivers/scsi/cxgb3i/cxgb3i_ddp.c b/drivers/scsi/cxgb3i/cxgb3i_ddp.c
index d06a661..99c9125 100644
--- a/drivers/scsi/cxgb3i/cxgb3i_ddp.c
+++ b/drivers/scsi/cxgb3i/cxgb3i_ddp.c
@@ -120,20 +120,26 @@ static void clear_ddp_map(struct cxgb3i_ddp_info *ddp, 
unsigned int tag,
 }
 
 static inline int ddp_find_unused_entries(struct cxgb3i_ddp_info *ddp,
-                                         int start, int max, int count,
+                                         unsigned int start, unsigned int max,
+                                         unsigned int count,
                                          struct cxgb3i_gather_list *gl)
 {
-       unsigned int i, j;
+       unsigned int i, j, k;
 
+       /* not enough entries */
+       if ((max - start) < count)
+               return -EBUSY;
+
+       max -= count;
        spin_lock(&ddp->map_lock);
-       for (i = start; i <= max;) {
-               for (j = 0; j < count; j++) {
-                       if (ddp->gl_map[i + j])
+       for (i = start; i < max;) {
+               for (j = 0, k = i; j < count; j++, k++) {
+                       if (ddp->gl_map[k])
                                break;
                }
                if (j == count) {
-                       for (j = 0; j < count; j++)
-                               ddp->gl_map[i + j] = gl;
+                       for (j = 0, k = i; j < count; j++, k++)
+                               ddp->gl_map[k] = gl;
                        spin_unlock(&ddp->map_lock);
                        return i;
                }
@@ -354,7 +360,7 @@ int cxgb3i_ddp_tag_reserve(struct t3cdev *tdev, unsigned 
int tid,
        struct cxgb3i_ddp_info *ddp = tdev->ulp_iscsi;
        struct pagepod_hdr hdr;
        unsigned int npods;
-       int idx = -1, idx_max;
+       int idx = -1;
        int err = -ENOMEM;
        u32 sw_tag = *tagp;
        u32 tag;
@@ -367,17 +373,17 @@ int cxgb3i_ddp_tag_reserve(struct t3cdev *tdev, unsigned 
int tid,
        }
 
        npods = (gl->nelem + PPOD_PAGES_MAX - 1) >> PPOD_PAGES_SHIFT;
-       idx_max = ddp->nppods - npods + 1;
 
        if (ddp->idx_last == ddp->nppods)
-               idx = ddp_find_unused_entries(ddp, 0, idx_max, npods, gl);
+               idx = ddp_find_unused_entries(ddp, 0, ddp->nppods, npods, gl);
        else {
                idx = ddp_find_unused_entries(ddp, ddp->idx_last + 1,
-                                             idx_max, npods, gl);
-               if (idx < 0 && ddp->idx_last >= npods)
+                                             ddp->nppods, npods, gl);
+               if (idx < 0 && ddp->idx_last >= npods) {
                        idx = ddp_find_unused_entries(ddp, 0,
-                                                     ddp->idx_last - npods + 1,
+                               min(ddp->idx_last + npods, ddp->nppods),
                                                      npods, gl);
+               }
        }
        if (idx < 0) {
                ddp_log_debug("xferlen %u, gl %u, npods %u NO DDP.\n",

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