Messages in this thread Patch in this message | | | Date | Wed, 20 Aug 2008 00:47:23 -0700 | From | Zev Weiss <> | Subject | [PATCH] [MTD] mtdchar.c: Fix regression in MEMGETREGIONINFO ioctl() |
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From: Zev Weiss <zevweiss@gmail.com>
The MEMGETREGIONINFO ioctl() in mtdchar.c was clobbering user memory by overwriting more than intended, due to the size of struct mtd_erase_region_info changing in commit 0ecbc81adfcb9f15f86b05ff576b342ce81bbef8.
Fix uses a member-by-member copy into a local struct region_info_user, which is then copy_to_user()'d (and matches the size correctly by being of the same type as the pointer passed in the ioctl() call).
Signed-off-by: Zev Weiss <zevweiss@gmail.com> Tested-by: Zev Weiss <zevweiss@gmail.com> --- I had been having some problems with userspace memory corruption, and traced them to a MEMGETREGIONINFO ioctl() on an MTD device. I applied this patch and it seems to fix the problem, though I am not an expert and there may be a more correct way to go about doing this. I'm also new at submitting patches, so hopefully I haven't screwed up the patch-submission etiquette too horrifically.
drivers/mtd/mtdchar.c | 11 +++++++++-- 1 files changed, 9 insertions(+), 2 deletions(-)
diff --git a/drivers/mtd/mtdchar.c b/drivers/mtd/mtdchar.c index 13cc67a..0acb135 100644 --- a/drivers/mtd/mtdchar.c +++ b/drivers/mtd/mtdchar.c @@ -411,14 +411,21 @@ static int mtd_ioctl(struct inode *inode, struct file *file, case MEMGETREGIONINFO: { struct region_info_user ur; + struct mtd_erase_region_info *kr;
if (copy_from_user(&ur, argp, sizeof(struct region_info_user))) return -EFAULT;
if (ur.regionindex >= mtd->numeraseregions) return -EINVAL; - if (copy_to_user(argp, &(mtd->eraseregions[ur.regionindex]), - sizeof(struct mtd_erase_region_info))) + + kr = &(mtd->eraseregions[ur.regionindex]); + + ur.offset = kr->offset; + ur.erasesize = kr->erasesize; + ur.numblocks = kr->numblocks; + + if (copy_to_user(argp, &ur, sizeof(struct region_info_user))) return -EFAULT; break; }
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