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Date: Mon, 12 Mar 2018 13:48:57 +0100
From: Salvatore Mesoraca <s.mesoraca16@...il.com>
To: linux-kernel@...r.kernel.org
Cc: kernel-hardening@...ts.openwall.com,
linux-scsi@...r.kernel.org,
"James E.J. Bottomley" <jejb@...ux.vnet.ibm.com>,
"Martin K. Petersen" <martin.petersen@...cle.com>,
"Tobin C. Harding" <tobin@...orbit.com>,
Dario Ballabio <ballabio_dario@....com>,
Kees Cook <keescook@...omium.org>,
Salvatore Mesoraca <s.mesoraca16@...il.com>,
valdis.kletnieks@...edu
Subject: [PATCH v2] scsi: eata: drop VLA in reorder()
Avoid 3 VLAs[1] by using a single dinamically allocated array
and some helper variables: we don't need 3 arrays.
[1] https://lkml.org/lkml/2018/3/7/621
Signed-off-by: Salvatore Mesoraca <s.mesoraca16@...il.com>
---
drivers/scsi/eata.c | 40 ++++++++++++++++++++++++++--------------
1 file changed, 26 insertions(+), 14 deletions(-)
diff --git a/drivers/scsi/eata.c b/drivers/scsi/eata.c
index 6501c33..8ba44b7 100644
--- a/drivers/scsi/eata.c
+++ b/drivers/scsi/eata.c
@@ -2091,12 +2091,14 @@ static void sort(unsigned long sk[], unsigned int da[], unsigned int n,
static int reorder(struct hostdata *ha, unsigned long cursec,
unsigned int ihdlr, unsigned int il[], unsigned int n_ready)
{
+ int overlap;
struct scsi_cmnd *SCpnt;
struct mscp *cpp;
unsigned int k, n;
unsigned int rev = 0, s = 1, r = 1;
- unsigned int input_only = 1, overlap = 0;
- unsigned long sl[n_ready], pl[n_ready], ll[n_ready];
+ unsigned int input_only = 1;
+ unsigned long *sl;
+ unsigned long sl_zero, sl_cur, sl_prev, ll_cur, ll_prev;
unsigned long maxsec = 0, minsec = ULONG_MAX, seek = 0, iseek = 0;
unsigned long ioseek = 0;
@@ -2115,6 +2117,12 @@ static int reorder(struct hostdata *ha, unsigned long cursec,
if (n_ready <= 1)
return 0;
+ overlap = -ENOMEM;
+ sl = kcalloc(n_ready, sizeof(*sl), GFP_ATOMIC);
+ if (!sl)
+ goto out;
+ overlap = 0;
+
for (n = 0; n < n_ready; n++) {
k = il[n];
cpp = &ha->cp[k];
@@ -2164,31 +2172,33 @@ static int reorder(struct hostdata *ha, unsigned long cursec,
if (!((rev && r) || (!rev && s)))
sort(sl, il, n_ready, rev);
+ sl_zero = sl[0];
+
if (!input_only)
for (n = 0; n < n_ready; n++) {
k = il[n];
cpp = &ha->cp[k];
SCpnt = cpp->SCpnt;
- ll[n] = blk_rq_sectors(SCpnt->request);
- pl[n] = SCpnt->serial_number;
+ ll_cur = blk_rq_sectors(SCpnt->request);
+ sl_cur = sl[n];
+ sl[n] = SCpnt->serial_number;
- if (!n)
- continue;
-
- if ((sl[n] == sl[n - 1])
- || (!rev && ((sl[n - 1] + ll[n - 1]) > sl[n]))
- || (rev && ((sl[n] + ll[n]) > sl[n - 1])))
+ if (n && ((sl_cur == sl_prev)
+ || (!rev && ((sl_prev + ll_prev) > sl_cur))
+ || (rev && ((sl_cur + ll_cur) > sl_prev))))
overlap = 1;
+ ll_prev = ll_cur;
+ sl_prev = sl_cur;
}
if (overlap)
- sort(pl, il, n_ready, 0);
+ sort(sl, il, n_ready, 0);
if (link_statistics) {
- if (cursec > sl[0])
- iseek = cursec - sl[0];
+ if (cursec > sl_zero)
+ iseek = cursec - sl_zero;
else
- iseek = sl[0] - cursec;
+ iseek = sl_zero - cursec;
batchcount++;
readycount += n_ready;
seeknosort += seek / 1024;
@@ -2225,6 +2235,8 @@ static int reorder(struct hostdata *ha, unsigned long cursec,
YESNO(overlap), cpp->din);
}
#endif
+ kfree(sl);
+out:
return overlap;
}
--
1.9.1
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