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authorDan Carpenter <dan.carpenter@oracle.com>2019-08-21 10:24:56 +0300
committerNoralf Trønnes <noralf@tronnes.org>2019-08-26 15:50:55 +0300
commitd72cf01f410aa09868d98b672f3f92328c96b32d (patch)
treea1e21abcd34b9e5d5a47d090cbb9314e303557ed /drivers/gpu/drm/drm_mipi_dbi.c
parent6dbe0c4b0fc0646442b2b1580d022404e582fd7b (diff)
downloadlinux-d72cf01f410aa09868d98b672f3f92328c96b32d.tar.xz
drm/mipi-dbi: fix a loop in debugfs code
This code will likely crash if we try to do a zero byte write. The code looks like this: /* strip trailing whitespace */ for (i = count - 1; i > 0; i--) if (isspace(buf[i])) ... We're writing zero bytes so count = 0. You would think that "count - 1" would be negative one, but because "i" is unsigned it is a large positive numer instead. The "i > 0" condition is true and the "buf[i]" access will be out of bounds. The fix is to make "i" signed and now everything works as expected. The upper bound of "count" is capped in __kernel_write() at MAX_RW_COUNT so we don't have to worry about it being higher than INT_MAX. Fixes: 02dd95fe3169 ("drm/tinydrm: Add MIPI DBI support") Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com> [noralf: Adjust title] Signed-off-by: Noralf Trønnes <noralf@tronnes.org> Link: https://patchwork.freedesktop.org/patch/msgid/20190821072456.GJ26957@mwanda
Diffstat (limited to 'drivers/gpu/drm/drm_mipi_dbi.c')
-rw-r--r--drivers/gpu/drm/drm_mipi_dbi.c3
1 files changed, 1 insertions, 2 deletions
diff --git a/drivers/gpu/drm/drm_mipi_dbi.c b/drivers/gpu/drm/drm_mipi_dbi.c
index 1961f713aaab..c4ee2709a6f3 100644
--- a/drivers/gpu/drm/drm_mipi_dbi.c
+++ b/drivers/gpu/drm/drm_mipi_dbi.c
@@ -1187,8 +1187,7 @@ static ssize_t mipi_dbi_debugfs_command_write(struct file *file,
struct mipi_dbi_dev *dbidev = m->private;
u8 val, cmd = 0, parameters[64];
char *buf, *pos, *token;
- unsigned int i;
- int ret, idx;
+ int i, ret, idx;
if (!drm_dev_enter(&dbidev->drm, &idx))
return -ENODEV;