[Devel] [PATCH RHEL10 COMMIT] dm-ploop: use the ERRNO fault injection class for ploop_get_delta_file()

[Konstantin Khorenko <khorenko@virtuozzo.com>]

The commit is pushed to "branch-rh10-6.12.0-211.39.1.16.x.vz10-ovz" and will appear at git at bitbucket.org:openvz/vzkernel.git
after rh10-6.12.0-211.39.1.16.6.vz10
------>
commit 1ab5dd2ffa73d34985c1e57dd4e3ab27c04fb4d4
Author: Konstantin Khorenko <khorenko@virtuozzo.com>
Date:   Wed Aug 19 18:33:35 2026 +0200

    dm-ploop: use the ERRNO fault injection class for ploop_get_delta_file()
    
    ploop_get_delta_file() returns a valid struct file * or an ERR_PTR(),
    never NULL, and its only caller relies on exactly that.
    
    The function, however, is annotated as
    
            ALLOW_ERROR_INJECTION(ploop_get_delta_file, ERRNO_NULL);
    
    So injecting a failure the default way makes the function return NULL,
    the NULL sails past IS_ERR() and vfs_fsync() dereferences it.
    
    This is the annotation misdescribing the function rather than a missing
    check in the caller: NULL is not a value ploop_get_delta_file() can ever
    return. Use the ERRNO class, which injects error pointers only.
    
    Fixes: 4fc49f0700e2 ("dm-ploop: Allow fault injection for all ploop functions")
    Feature: dm-ploop: ploop target driver
    https://virtuozzo.atlassian.net/browse/VSTOR-137234
    Signed-off-by: Konstantin Khorenko <khorenko@virtuozzo.com>
    Reviewed-by: Pavel Tikhomirov <ptikhomirov@virtuozzo.com>
---
 drivers/md/dm-ploop-target.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/md/dm-ploop-target.c b/drivers/md/dm-ploop-target.c
index 0de0e84d440d0..7dab95402def7 100644
--- a/drivers/md/dm-ploop-target.c
+++ b/drivers/md/dm-ploop-target.c
@@ -255,7 +255,7 @@ static struct file *ploop_get_delta_file(struct ploop *ploop, int fd)
 	return ERR_PTR(ret);
 
 }
-ALLOW_ERROR_INJECTION(ploop_get_delta_file, ERRNO_NULL);
+ALLOW_ERROR_INJECTION(ploop_get_delta_file, ERRNO);
 
 static int ploop_check_top_delta(struct ploop *ploop, struct file *file)
 {