[PATCH next] mtd: maps: physmap: Fix infinite loop crash in ROM type probing

Discussion:

Geert Uytterhoeven

2018-11-06 21:44:16 UTC

On Toshiba RBTX4927, where map_probe is supposed to fail:

Creating 2 MTD partitions on "physmap-flash.0":
0x000000c00000-0x000001000000 : "boot"
0x000000000000-0x000000c00000 : "user"
physmap-flash physmap-flash.1: physmap platform flash device: [mem 0x1e000000-0x1effffff]
CPU 0 Unable to handle kernel paging request at virtual address 00000000, epc == 80320f40, ra == 80321004
...
Call Trace:
[<80320f40>] get_mtd_chip_driver+0x30/0x8c
[<80321004>] do_map_probe+0x20/0x90
[<80328448>] physmap_flash_probe+0x484/0x4ec

The access to rom_probe_types[] was changed from a sentinel-based loop
to an infinite loop, causing a crash when reaching the sentinel.

Fix this by:
- Removing the no longer needed sentinel,
- Limiting the number of loop iterations to the actual number of ROM
types.

Fixes: c7afe08496fa463e ("mtd: maps: physmap: Invert logic on if/else branch")
Signed-off-by: Geert Uytterhoeven <***@linux-m68k.org>
---
drivers/mtd/maps/physmap-core.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/mtd/maps/physmap-core.c b/drivers/mtd/maps/physmap-core.c
index 33b77bd9022ce251..e8c3b250d8421edc 100644
--- a/drivers/mtd/maps/physmap-core.c
+++ b/drivers/mtd/maps/physmap-core.c
@@ -396,7 +396,7 @@ static int physmap_flash_of_init(struct platform_device *dev)
#endif /* IS_ENABLED(CONFIG_MTD_PHYSMAP_OF) */

static const char * const rom_probe_types[] = {
- "cfi_probe", "jedec_probe", "qinfo_probe", "map_rom", NULL
+ "cfi_probe", "jedec_probe", "qinfo_probe", "map_rom",
};

static const char * const part_probe_types[] = {
@@ -524,7 +524,7 @@ static int physmap_flash_probe(struct platform_device *dev)
} else {
int j;

- for (j = 0; ARRAY_SIZE(rom_probe_types); j++) {
+ for (j = 0; j < ARRAY_SIZE(rom_probe_types); j++) {
info->mtds[i] = do_map_probe(rom_probe_types[j],
&info->maps[i]);
if (info->mtds[i])

--
2.17.1

Boris Brezillon

2018-11-06 21:58:29 UTC

Permalink

On Tue, 6 Nov 2018 22:44:16 +0100

Post by Geert Uytterhoeven
0x000000c00000-0x000001000000 : "boot"
0x000000000000-0x000000c00000 : "user"
physmap-flash physmap-flash.1: physmap platform flash device: [mem 0x1e000000-0x1effffff]
CPU 0 Unable to handle kernel paging request at virtual address 00000000, epc == 80320f40, ra == 80321004
...
[<80320f40>] get_mtd_chip_driver+0x30/0x8c
[<80321004>] do_map_probe+0x20/0x90
[<80328448>] physmap_flash_probe+0x484/0x4ec
The access to rom_probe_types[] was changed from a sentinel-based loop
to an infinite loop, causing a crash when reaching the sentinel.

Oops. Do you mind if I fix that in-place (squash your changes in
Ricardo's original commit)?

Post by Geert Uytterhoeven
- Removing the no longer needed sentinel,
- Limiting the number of loop iterations to the actual number of ROM
types.
Fixes: c7afe08496fa463e ("mtd: maps: physmap: Invert logic on if/else branch")
---
drivers/mtd/maps/physmap-core.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)
diff --git a/drivers/mtd/maps/physmap-core.c b/drivers/mtd/maps/physmap-core.c
index 33b77bd9022ce251..e8c3b250d8421edc 100644
--- a/drivers/mtd/maps/physmap-core.c
+++ b/drivers/mtd/maps/physmap-core.c
@@ -396,7 +396,7 @@ static int physmap_flash_of_init(struct platform_device *dev)
#endif /* IS_ENABLED(CONFIG_MTD_PHYSMAP_OF) */
static const char * const rom_probe_types[] = {
- "cfi_probe", "jedec_probe", "qinfo_probe", "map_rom", NULL
+ "cfi_probe", "jedec_probe", "qinfo_probe", "map_rom",
};
static const char * const part_probe_types[] = {
@@ -524,7 +524,7 @@ static int physmap_flash_probe(struct platform_device *dev)
} else {
int j;
- for (j = 0; ARRAY_SIZE(rom_probe_types); j++) {
+ for (j = 0; j < ARRAY_SIZE(rom_probe_types); j++) {
info->mtds[i] = do_map_probe(rom_probe_types[j],
&info->maps[i]);
if (info->mtds[i])

Geert Uytterhoeven

2018-11-06 22:19:14 UTC

Permalink

Hi Boris,

On Tue, Nov 6, 2018 at 10:58 PM Boris Brezillon

Post by Boris Brezillon
On Tue, 6 Nov 2018 22:44:16 +0100

Oops. Do you mind if I fix that in-place (squash your changes in
Ricardo's original commit)?

No problem. Thanks!

Gr{oetje,eeting}s,

Geert

--
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- ***@linux-m68k.org

In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
-- Linus Torvalds

Boris Brezillon

2018-11-06 22:34:32 UTC

Permalink

On Tue, 6 Nov 2018 23:19:14 +0100

Post by Geert Uytterhoeven
Hi Boris,
On Tue, Nov 6, 2018 at 10:58 PM Boris Brezillon

Post by Boris Brezillon
On Tue, 6 Nov 2018 22:44:16 +0100

Oops. Do you mind if I fix that in-place (squash your changes in
Ricardo's original commit)?

Done.

Post by Geert Uytterhoeven
No problem. Thanks!

Thanks for reporting/fixing the bug.

Boris

Ricardo Ribalda Delgado

2018-11-07 07:33:57 UTC

Permalink

Hi Boris and Geert

On Tue, Nov 6, 2018 at 11:34 PM Boris Brezillon

Post by Boris Brezillon
On Tue, 6 Nov 2018 23:19:14 +0100

Post by Geert Uytterhoeven
Hi Boris,
On Tue, Nov 6, 2018 at 10:58 PM Boris Brezillon

Post by Boris Brezillon
On Tue, 6 Nov 2018 22:44:16 +0100

Oops. Do you mind if I fix that in-place (squash your changes in
Ricardo's original commit)?

Done.

Post by Geert Uytterhoeven
No problem. Thanks!

Thanks to both of you for fixing this .

Post by Boris Brezillon
Thanks for reporting/fixing the bug.
Boris

--
Ricardo Ribalda