[PATCH v3] pinctrl: mvebu: prevent walking off the end of group array

From: Sebastian Hesselbarth
Date: Sat Mar 16 2013 - 07:45:25 EST


From: David Woodhouse <dwmw2@xxxxxxxxxxxxx>

While investigating (ab)use of krealloc, David found this bug. It's
unlikely to occur, but now we detect the condition and error out
appropriately.

Signed-off-by: David Woodhouse <David.Woodhouse@xxxxxxxxx>
Signed-off-by: Jason Cooper <jason@xxxxxxxxxxxxxx>
Signed-off-by: Sebastian Hesselbarth <sebastian.hesselbarth@xxxxxxxxx>
---
Jason, David,

I tested the patch on Dove and fixed all remaining issues.

Thomas, Gregory, Andrew should test on their platforms, too.

Sebastian

Changes from v2:
- fix counting of available array space
- fix return code handling

Changes from v1:
- correct typo (s/ nt / int /) I should've caught before sending.

drivers/pinctrl/mvebu/pinctrl-mvebu.c | 33 +++++++++++++++++++++------------
1 file changed, 21 insertions(+), 12 deletions(-)
---
Cc: Jason Cooper <jason@xxxxxxxxxxxxxx>
Cc: David Woodhouse <dwmw2@xxxxxxxxxxxxx>
Cc: Sebastian Hesselbarth <sebastian.hesselbarth@xxxxxxxxx>
Cc: Thomas Petazzoni <thomas.petazzoni@xxxxxxxxxxxxxxxxxx>
Cc: Gregory Clement <gregory.clement@xxxxxxxxxxxxxxxxxx>
Cc: Andrew Lunn <andrew@xxxxxxx>
Cc: Ezequiel Garcia <ezequiel.garcia@xxxxxxxxxxxxxxxxxx>
Cc: Linus Walleij <linus.walleij@xxxxxxxxxx>
Cc: Stephen Warren <swarren@xxxxxxxxxxxxx>
Cc: Linux ARM Kernel <linux-arm-kernel@xxxxxxxxxxxxxxxxxxx>
Cc: linux-kernel@xxxxxxxxxxxxxxx
---
diff --git a/drivers/pinctrl/mvebu/pinctrl-mvebu.c b/drivers/pinctrl/mvebu/pinctrl-mvebu.c
index c689c04..aa77fb7a 100644
--- a/drivers/pinctrl/mvebu/pinctrl-mvebu.c
+++ b/drivers/pinctrl/mvebu/pinctrl-mvebu.c
@@ -478,8 +478,12 @@ static struct pinctrl_ops mvebu_pinctrl_ops = {
.dt_free_map = mvebu_pinctrl_dt_free_map,
};

-static int _add_function(struct mvebu_pinctrl_function *funcs, const char *name)
+static int _add_function(struct mvebu_pinctrl_function *funcs, int *funcsize,
+ const char *name)
{
+ if (*funcsize <= 0)
+ return -EOVERFLOW;
+
while (funcs->num_groups) {
/* function already there */
if (strcmp(funcs->name, name) == 0) {
@@ -488,8 +492,12 @@ static int _add_function(struct mvebu_pinctrl_function *funcs, const char *name)
}
funcs++;
}
+
+ /* append new unique function */
funcs->name = name;
funcs->num_groups = 1;
+ (*funcsize)--;
+
return 0;
}

@@ -497,12 +505,12 @@ static int mvebu_pinctrl_build_functions(struct platform_device *pdev,
struct mvebu_pinctrl *pctl)
{
struct mvebu_pinctrl_function *funcs;
- int num = 0;
+ int num = 0, funcsize = pctl->desc.npins;
int n, s;

/* we allocate functions for number of pins and hope
- * there are less unique functions than pins available */
- funcs = devm_kzalloc(&pdev->dev, pctl->desc.npins *
+ * there are fewer unique functions than pins available */
+ funcs = devm_kzalloc(&pdev->dev, funcsize *
sizeof(struct mvebu_pinctrl_function), GFP_KERNEL);
if (!funcs)
return -ENOMEM;
@@ -510,26 +518,27 @@ static int mvebu_pinctrl_build_functions(struct platform_device *pdev,
for (n = 0; n < pctl->num_groups; n++) {
struct mvebu_pinctrl_group *grp = &pctl->groups[n];
for (s = 0; s < grp->num_settings; s++) {
+ int ret;
+
/* skip unsupported settings on this variant */
if (pctl->variant &&
!(pctl->variant & grp->settings[s].variant))
continue;

/* check for unique functions and count groups */
- if (_add_function(funcs, grp->settings[s].name))
+ ret = _add_function(funcs, &funcsize,
+ grp->settings[s].name);
+ if (ret == -EOVERFLOW)
+ dev_err(&pdev->dev,
+ "More functions than pins(%d)\n",
+ pctl->desc.npins);
+ if (ret < 0)
continue;

num++;
}
}

- /* with the number of unique functions and it's groups known,
- reallocate functions and assign group names */
- funcs = krealloc(funcs, num * sizeof(struct mvebu_pinctrl_function),
- GFP_KERNEL);
- if (!funcs)
- return -ENOMEM;
-
pctl->num_functions = num;
pctl->functions = funcs;

--
1.7.10.4

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