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authorDan Carpenter <dan.carpenter@oracle.com>2022-01-21 14:55:05 +0300
committerMiquel Raynal <miquel.raynal@bootlin.com>2022-01-25 12:32:07 +0300
commit3e3765875b1b8864898603768fd5c93eeb552211 (patch)
treecc469397df15bc29a8360eb14a716788f3935090 /drivers/mtd/devices
parent4cd335dae3cf25412427938d8abbaf04d46e63b5 (diff)
downloadlinux-3e3765875b1b8864898603768fd5c93eeb552211.tar.xz
mtd: phram: Prevent divide by zero bug in phram_setup()
The problem is that "erasesize" is a uint64_t type so it might be non-zero but the lower 32 bits are zero so when it's truncated, "(uint32_t)erasesize", then that value is zero. This leads to a divide by zero bug. Avoid the bug by delaying the divide until after we have validated that "erasesize" is non-zero and within the uint32_t range. Fixes: dc2b3e5cbc80 ("mtd: phram: use div_u64_rem to stop overwrite len in phram_setup") Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com> Signed-off-by: Miquel Raynal <miquel.raynal@bootlin.com> Link: https://lore.kernel.org/linux-mtd/20220121115505.GI1978@kadam
Diffstat (limited to 'drivers/mtd/devices')
-rw-r--r--drivers/mtd/devices/phram.c12
1 files changed, 8 insertions, 4 deletions
diff --git a/drivers/mtd/devices/phram.c b/drivers/mtd/devices/phram.c
index 6ed6c51fac69..d503821a3e60 100644
--- a/drivers/mtd/devices/phram.c
+++ b/drivers/mtd/devices/phram.c
@@ -264,16 +264,20 @@ static int phram_setup(const char *val)
}
}
- if (erasesize)
- div_u64_rem(len, (uint32_t)erasesize, &rem);
-
if (len == 0 || erasesize == 0 || erasesize > len
- || erasesize > UINT_MAX || rem) {
+ || erasesize > UINT_MAX) {
parse_err("illegal erasesize or len\n");
ret = -EINVAL;
goto error;
}
+ div_u64_rem(len, (uint32_t)erasesize, &rem);
+ if (rem) {
+ parse_err("len is not multiple of erasesize\n");
+ ret = -EINVAL;
+ goto error;
+ }
+
ret = register_device(name, start, len, (uint32_t)erasesize);
if (ret)
goto error;