[BUG] jfs: possible uninitialized-variable access in xtSplitUp()

[Li Tuo]

Hello,

Our static analysis tool finds a possible uninitialized-variable access 
in the jfs driver in Linux 5.14.0-rc3:

At the beginning of the function xtSplitUp(), the variable rbn is not 
initialized.
If sp->header.flag & BT_ROOT is true,
780:    rc = (sp->header.flag & BT_ROOT) ? xtSplitRoot(tid, ip, split, 
&rmp) : xtSplitPage(tid, ip, split, &rmp, &rbn);

the varialbe rbn will remain uninitialized.
However, it is accessed through:
814:    rcbn = rbn;

I am not quite sure whether this possible uninitialized-variable access 
is real and how to fix it if it is real.
Any feedback would be appreciated, thanks!

Reported-by: TOTE Robot <oslab@xxxxxxxxxxxxxxx>

Best wishes,
Tuo Li