[PATCH 1/2] hw/ide/core.c (cmd_read_native_max): Avoid limited device parameters

[Lev Kujawski]

Always use the native CHS device parameters for the ATA commands READ
NATIVE MAX ADDRESS and READ NATIVE MAX ADDRESS EXT, not those limited
by the ATA command INITIALIZE_DEVICE_PARAMETERS (introduced in patch
176e4961, hw/ide/core.c: Implement ATA INITIALIZE_DEVICE_PARAMETERS
command, 2022-07-07.)

As stated by the ATA/ATAPI specification, "[t]he native maximum is the
highest address accepted by the device in the factory default
condition."  Therefore this patch substitutes the native values in
drive_heads and drive_sectors before calling ide_set_sector().

One consequence of the prior behavior was that setting zero sectors
per track could lead to an FPE within ide_set_sector().  Thanks to
Alexander Bulekov for reporting this issue.

Resolves: https://gitlab.com/qemu-project/qemu/-/issues/1243
Signed-off-by: Lev Kujawski <lkujaw@mailbox.org>
---
 hw/ide/core.c | 21 +++++++++++++++++----
 1 file changed, 17 insertions(+), 4 deletions(-)

diff --git a/hw/ide/core.c b/hw/ide/core.c
index 39afdc0006..ee836401bc 100644
--- a/hw/ide/core.c
+++ b/hw/ide/core.c
@@ -1608,11 +1608,24 @@ static bool cmd_read_native_max(IDEState *s, uint8_t 
cmd)
     /* Refuse if no sectors are addressable (e.g. medium not inserted) */
     if (s->nb_sectors == 0) {
         ide_abort_command(s);
-        return true;
-    }
+    } else {
+        /*
+         * Save the active drive parameters, which may have been
+         * limited from their native counterparts by, e.g., INITIALIZE
+         * DEVICE PARAMETERS or SET MAX ADDRESS.
+         */
+        const int aheads = s->heads;
+        const int asectors = s->sectors;
 
-    ide_cmd_lba48_transform(s, lba48);
-    ide_set_sector(s, s->nb_sectors - 1);
+        s->heads = s->drive_heads;
+        s->sectors = s->drive_sectors;
+
+        ide_cmd_lba48_transform(s, lba48);
+        ide_set_sector(s, s->nb_sectors - 1);
+
+        s->heads = aheads;
+        s->sectors = asectors;
+    }
 
     return true;
 }
-- 
2.34.1