[v3] EDAC/i10nm: Fix an inappropriate shift exponent

Commit Message

Koba Ko July 4, 2023, 9:59 a.m. UTC

A surprising value was determined after a read failure from a DIMM.

Software analyses pointed a data processing issue out.
`UBSAN: shift-out-of-bounds in drivers/edac/skx_common.c:369:16
 shift exponent -66 is negative`

A special value combination could not be handled so far.

Check if an invalid value was detected by a call of the function “skx_get_dimm_attr”.
* Print a corresponding error message in this case.
* Return zero then directly from the function “skx_get_dimm_info”.

Fixes: 4ec656bdf43a ("EDAC, skx_edac: Add EDAC driver for Skylake")
Signed-off-by: Koba Ko <[e-mail]>
---
v3: According to Markus' comments, simplify and polish the summary and add `Fixes:`
v2: make error-print explicitly

 drivers/edac/skx_common.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

Comments

Dan Carpenter July 4, 2023, 12:49 p.m. UTC | #1

Good enough for me, thanks.

Reviewed-by: Dan Carpenter <[e-mail]>

regards,
dan carpenter

Patch

diff --git a/drivers/edac/skx_common.c b/drivers/edac/skx_common.c
index 2a00e0503f0d5..ac61db72d2e6b 100644
--- a/drivers/edac/skx_common.c
+++ b/drivers/edac/skx_common.c
@@ -330,7 +330,7 @@  static int skx_get_dimm_attr(u32 reg, int lobit, int hibit, int add,
 	u32 val = GET_BITFIELD(reg, lobit, hibit);
 
 	if (val < minval || val > maxval) {
-		edac_dbg(2, "bad %s = %d (raw=0x%x)\n", name, val, reg);
+		skx_printk(KERN_ERR, "bad %s = %d (raw=0x%x)\n", name, val, reg);
 		return -EINVAL;
 	}
 	return val + add;
@@ -351,6 +351,8 @@  int skx_get_dimm_info(u32 mtr, u32 mcmtr, u32 amap, struct dimm_info *dimm,
 	ranks = numrank(mtr);
 	rows = numrow(mtr);
 	cols = imc->hbm_mc ? 6 : numcol(mtr);
+	if (ranks == -EINVAL || rows == -EINVAL || cols == -EINVAL)
+		return 0;
 
 	if (imc->hbm_mc) {
 		banks = 32;