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chardev/char-fe: Allow NULL chardev in qemu_chr_fe_init()

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All the functions in char-fe.c handle the CharBackend
having a NULL Chardev pointer, which means that the
backend exists but is not connected to anything. The
exception is qemu_chr_fe_init(), which will crash if
passed a NULL Chardev pointer argument. This can happen
for various boards if they're started with 'nodefaults':
 arm-softmmu/qemu-system-arm -S -nodefaults -M cubieboard
 riscv32-softmmu/qemu-system-riscv32 -nodefaults -M sifive_e

Make qemu_chr_fe_init() accept a NULL chardev. This allows
UART models to handle NULL chardev properties without
generally needing to special case them or to manually
create a NullChardev.

Reported-by: Thomas Huth <thuth@redhat.com>
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Message-Id: <20180323152948.27048-1-peter.maydell@linaro.org>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
This commit is contained in:
Peter Maydell 2018-03-23 15:29:48 +00:00 committed by Paolo Bonzini
parent 90c558beca
commit 12051d82f0
1 changed files with 12 additions and 10 deletions
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22
chardev/char-fe.c
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@ -198,19 +198,21 @@ bool qemu_chr_fe_init(CharBackend *b, Chardev *s, Error **errp)
{ {
int tag = 0; int tag = 0;
if (CHARDEV_IS_MUX(s)) { if (s) {
MuxChardev *d = MUX_CHARDEV(s); if (CHARDEV_IS_MUX(s)) {
MuxChardev *d = MUX_CHARDEV(s);
if (d->mux_cnt >= MAX_MUX) { if (d->mux_cnt >= MAX_MUX) {
goto unavailable;
}
d->backends[d->mux_cnt] = b;
tag = d->mux_cnt++;
} else if (s->be) {
goto unavailable; goto unavailable;
} else {
s->be = b;
} }
d->backends[d->mux_cnt] = b;
tag = d->mux_cnt++;
} else if (s->be) {
goto unavailable;
} else {
s->be = b;
} }
b->fe_open = false; b->fe_open = false;