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fbmem: don't call copy_from/to_user() with mutex held

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Avoid calling copy_from/to_user() with fb_info->lock mutex held in fbmem
ioctl().

fb_mmap() is called under mm->mmap_sem (A) held, that also acquires
fb_info->lock (B); fb_ioctl() takes fb_info->lock (B) and does
copy_from/to_user() that might acquire mm->mmap_sem (A), causing a
deadlock.

NOTE: it doesn't push down the fb_info->lock in each own driver's
fb_ioctl(), so there are still potential deadlocks elsewhere.

Signed-off-by: Andrea Righi <righi.andrea@gmail.com>
Cc: Dave Jones <davej@redhat.com>
Cc: "Rafael J. Wysocki" <rjw@sisk.pl>
Cc: Johannes Weiner <hannes@saeurebad.de>
Cc: Krzysztof Helt <krzysztof.h1@wp.pl>
Cc: Harvey Harrison <harvey.harrison@gmail.com>
Cc: Stefan Richter <stefanr@s5r6.in-berlin.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Andrea Righi
2009-02-04 15:12:03 -08:00
committed by Linus Torvalds
parent afd8d0f940
commit 1f5e31d7e5
3 changed files with 98 additions and 72 deletions
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20
drivers/video/fbcmap.c
View File

@ -250,10 +250,6 @@ int fb_set_user_cmap(struct fb_cmap_user *cmap, struct fb_info *info)
int rc, size = cmap->len * sizeof(u16);
struct fb_cmap umap;
if (cmap->start < 0 || (!info->fbops->fb_setcolreg &&
!info->fbops->fb_setcmap))
return -EINVAL;
memset(&umap, 0, sizeof(struct fb_cmap));
rc = fb_alloc_cmap(&umap, cmap->len, cmap->transp != NULL);
if (rc)
@ -262,11 +258,23 @@ int fb_set_user_cmap(struct fb_cmap_user *cmap, struct fb_info *info)
copy_from_user(umap.green, cmap->green, size) ||
copy_from_user(umap.blue, cmap->blue, size) ||
(cmap->transp && copy_from_user(umap.transp, cmap->transp, size))) {
fb_dealloc_cmap(&umap);
return -EFAULT;
rc = -EFAULT;
goto out;
}
umap.start = cmap->start;
if (!lock_fb_info(info)) {
rc = -ENODEV;
goto out;
}
if (cmap->start < 0 || (!info->fbops->fb_setcolreg &&
!info->fbops->fb_setcmap)) {
rc = -EINVAL;
goto out1;
}
rc = fb_set_cmap(&umap, info);
out1:
unlock_fb_info(info);
out:
fb_dealloc_cmap(&umap);
return rc;
}