kernel/linux
0
Fork 0
mirror of https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/ synced 2026-10-18 19:12:56 +00:00
Code Issues Releases Packages Activity
linux/drivers
History
Linus Torvalds bb25fd4926 drm/edid: fix objtool warning in drm_cvt_modes() 
commit d652d5f1ee upstream.

Commit 991fcb77f4 ("drm/edid: Fix uninitialized variable in
drm_cvt_modes()") just replaced one warning with another.

The original warning about a possibly uninitialized variable was due to
the compiler not being smart enough to see that the case statement
actually enumerated all possible cases.  And the initial fix was just to
add a "default" case that had a single "unreachable()", just to tell the
compiler that that situation cannot happen.

However, that doesn't actually fix the fundamental reason for the
problem: the compiler still doesn't see that the existing case
statements enumerate all possibilities, so the compiler will still
generate code to jump to that unreachable case statement.  It just won't
complain about an uninitialized variable any more.

So now the compiler generates code to our inline asm marker that we told
it would not fall through, and end end result is basically random.  We
have created a bridge to nowhere.

And then, depending on the random details of just exactly what the
compiler ends up doing, 'objtool' might end up complaining about the
conditional branches (for conditions that cannot happen, and that thus
will never be taken - but if the compiler was not smart enough to figure
that out, we can't expect objtool to do so) going off in the weeds.

So depending on how the compiler has laid out the result, you might see
something like this:

    drivers/gpu/drm/drm_edid.o: warning: objtool: do_cvt_mode() falls through to next function drm_mode_detailed.isra.0()

and now you have a truly inscrutable warning that makes no sense at all
unless you start looking at whatever random code the compiler happened
to generate for our bare "unreachable()" statement.

IOW, don't use "unreachable()" unless you have an _active_ operation
that generates code that actually makes it obvious that something is not
reachable (ie an UD instruction or similar).

Solve the "compiler isn't smart enough" problem by just marking one of
the cases as "default", so that even when the compiler doesn't otherwise
see that we've enumerated all cases, the compiler will feel happy and
safe about there always being a valid case that initializes the 'width'
variable.

This also generates better code, since now the compiler doesn't generate
comparisons for five different possibilities (the four real ones and the
one that can't happen), but just for the three real ones and "the rest"
(which is that last one).

A smart enough compiler that sees that we cover all the cases won't care.

Cc: Lyude Paul <lyude@redhat.com>
Cc: Ilia Mirkin <imirkin@alum.mit.edu>
Cc: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
History 2020-12-30 11:54:29 +01:00
..
accessibility speakup: fix uninitialized flush_lock 2020-12-30 11:53:44 +01:00
acpi ACPI: PNP: compare the string length in the matching_id() 2020-12-30 11:54:06 +01:00
amba ARM: tegra: Replace zero-length array with flexible-array 2020-06-15 23:08:28 -05:00
android binder: add flag to clear buffer on txn complete 2020-12-30 11:54:09 +01:00
ata libata-5.10-2020-10-30 2020-10-30 14:51:01 -07:00
atm atm: nicstar: Unmap DMA on send error 2020-11-18 16:42:07 -08:00
auxdisplay A trivial patch for auxdisplay: 2020-09-05 14:22:46 -07:00
base driver: core: Fix list corruption after device_del() 2020-12-30 11:54:26 +01:00
bcma bcma: use semicolons rather than commas to separate statements 2020-10-01 16:23:50 +03:00
block null_blk: Fail zone append to conventional zones 2020-12-30 11:54:29 +01:00
bluetooth Bluetooth: btusb: Fix detection of some fake CSR controllers with a bcdDevice val of 0x0134 2020-12-30 11:53:40 +01:00
bus bus: fsl-mc: fix error return code in fsl_mc_object_allocate() 2020-12-30 11:53:46 +01:00
cdrom gdrom: use bdev_check_media_change 2020-09-10 09:32:31 -06:00
char Char/Misc driver fixes for 5.10-rc4 2020-11-15 10:15:17 -08:00
clk clk: tegra: Do not return 0 on failure 2020-12-30 11:54:26 +01:00
clocksource clocksource/drivers/arm_arch_timer: Correct fault programming of CNTKCTL_EL1.EVNTI 2020-12-30 11:53:37 +01:00
connector connector: simplify the return expression of cn_add_callback() 2020-09-21 13:48:29 -07:00
counter counter: microchip-tcb-capture: Fix CMR value check 2020-12-30 11:54:26 +01:00
cpufreq cpufreq: intel_pstate: Use most recent guaranteed performance values 2020-12-30 11:54:10 +01:00
cpuidle cpuidle: tegra: Annotate tegra_pm_set_cpu_in_lp2() with RCU_NONIDLE 2020-11-16 13:24:32 +01:00
crypto crypto: atmel-i2c - select CONFIG_BITREVERSE 2020-12-30 11:53:50 +01:00
dax device-dax/core: Fix memory leak when rmmod dax.ko 2020-12-30 11:54:26 +01:00
dca dca: Use PTR_ERR_OR_ZERO() to simplify code 2020-05-15 16:25:20 +02:00
devfreq PM / devfreq: tegra30: Improve initial hardware resetting 2020-09-29 17:50:10 +09:00
dio maccess: rename probe_kernel_{read,write} to copy_{from,to}_kernel_nofault 2020-06-17 10:57:41 -07:00
dma dmaengine: ti: k3-udma: Correct normal channel offset when uchan_cnt is not 0 2020-12-30 11:53:51 +01:00
dma-buf dma-buf/dma-resv: Respect num_fences when initializing the shared fence list. 2020-12-30 11:54:26 +01:00
edac EDAC/amd64: Fix PCI component registration 2020-12-30 11:54:11 +01:00
eisa treewide: replace '---help---' in Kconfig files with 'help' 2020-06-14 01:57:21 +09:00
extcon extcon: max77693: Fix modalias string 2020-12-30 11:53:49 +01:00
firewire firewire-ohci: use dma_alloc_pages 2020-09-25 06:20:48 +02:00
firmware mm/gup: prevent gup_fast from racing with COW during fork 2020-12-30 11:53:54 +01:00
fpga fpga: Specify HAS_IOMEM dependency for FPGA_DFL 2020-12-01 18:46:24 +01:00
fsi fsi: Aspeed: Add mutex to protect HW access 2020-12-30 11:53:46 +01:00
gnss treewide: replace '---help---' in Kconfig files with 'help' 2020-06-14 01:57:21 +09:00
gpio gpiolib: irq hooks: fix recursion in gpiochip_irq_unmask 2020-12-30 11:53:51 +01:00
gpu drm/edid: fix objtool warning in drm_cvt_modes() 2020-12-30 11:54:29 +01:00
greybus drivers/greybus: Use kobj_to_dev() 2020-09-04 18:06:01 +02:00
hid HID: i2c-hid: add Vero K147 to descriptor override 2020-12-26 16:02:43 +01:00
hsi HSI: omap_ssi: Don't jump to free ID in ssi_add_controller() 2020-12-30 11:53:24 +01:00
hv hyperv-fixes for 5.10-rc5 2020-11-16 15:02:33 -08:00
hwmon hwmon: (ina3221) Fix PM usage counter unbalance in ina3221_write_enable 2020-12-30 11:53:31 +01:00
hwspinlock hwspinlock: qcom: Allow mmio usage in addition to syscon 2020-07-13 22:29:28 -07:00
hwtracing coresight: remove broken __exit annotations 2020-12-30 11:53:44 +01:00
i2c Revert "i2c: i2c-qcom-geni: Fix DMA transfer race" 2020-12-30 11:52:57 +01:00
i3c * Fix DAA for the pre-reserved address case 2020-10-17 11:01:01 -07:00
ide block-5.10-2020-10-12 2020-10-13 12:12:44 -07:00
idle intel_idle: Build fix 2020-12-03 10:00:23 +01:00
iio iio:adc:ti-ads124s08: Fix alignment and data leak issues. 2020-12-30 11:54:25 +01:00
infiniband RDMA/cma: Don't overwrite sgid_attr after device is released 2020-12-30 11:53:53 +01:00
input Input: cyapa_gen6 - fix out-of-bounds stack access 2020-12-30 11:54:05 +01:00
interconnect interconnect: fix memory trashing in of_count_icc_providers() 2020-11-20 16:01:35 +02:00
iommu iommu/arm-smmu-qcom: Implement S2CR quirk 2020-12-30 11:54:15 +01:00
ipack treewide: replace '---help---' in Kconfig files with 'help' 2020-06-14 01:57:21 +09:00
irqchip irqchip/qcom-pdc: Fix phantom irq when changing between rising/falling 2020-12-30 11:53:51 +01:00
isdn treewide: Use fallthrough pseudo-keyword 2020-08-23 17:36:59 -05:00
leds leds: turris-omnia: check for LED_COLOR_ID_RGB instead LED_COLOR_ID_MULTI 2020-12-30 11:53:22 +01:00
lightnvm lightnvm: fix out-of-bounds write to array devices->info[] 2020-10-16 09:28:45 -06:00
macintosh macintosh/adb-iop: Send correct poll command 2020-12-30 11:53:39 +01:00
mailbox mailbox: arm_mhu_db: Fix mhu_db_shutdown by replacing kfree with devm_kfree 2020-12-30 11:53:28 +01:00
mcb drivers: mcb: use symbol namespaces 2019-11-03 19:54:53 +01:00
md md/cluster: fix deadlock when node is doing resync job 2020-12-30 11:54:25 +01:00
media media: ipu3-cio2: Make the field on subdev format V4L2_FIELD_NONE 2020-12-30 11:54:05 +01:00
memory memory: renesas-rpc-if: Fix unbalanced pm_runtime_enable in rpcif_{enable,disable}_rpm 2020-12-30 11:54:27 +01:00
memstick memstick: r592: Fix error return in r592_probe() 2020-12-30 11:53:34 +01:00
message scsi: mptfusion: Fix null pointer dereferences in mptscsih_remove() 2020-10-26 16:57:18 -04:00
mfd mfd: cpcap: Fix interrupt regression with regmap clear_ack 2020-12-30 11:53:16 +01:00
misc misc: pci_endpoint_test: fix return value of error branch 2020-12-30 11:53:45 +01:00
mmc mmc: pxamci: Fix error return code in pxamci_probe 2020-12-30 11:53:20 +01:00
most drivers: most: add character device interface driver 2020-09-07 15:16:26 +02:00
mtd mtd: rawnand: meson: fix meson_nfc_dma_buffer_release() arguments 2020-12-30 11:54:23 +01:00
mux treewide: Use fallthrough pseudo-keyword 2020-08-23 17:36:59 -05:00
net mt76: add back the SUPPORTS_REORDERING_BUFFER flag 2020-12-30 11:54:28 +01:00
nfc nfc: s3fwrn5: Release the nfc firmware 2020-12-30 11:53:53 +01:00
ntb Bug fixes for v5.10 2020-10-25 11:12:31 -07:00
nubus nubus: Remove cast to void pointer 2019-10-21 09:08:15 +02:00
nvdimm libnvdimm/namespace: Fix reaping of invalidated block-window-namespace labels 2020-12-30 11:54:27 +01:00
nvme nvme: fix memory leak freeing command effects 2020-11-14 09:57:55 +01:00
nvmem nvmem: core: fix possibly memleak when use nvmem_cell_info_to_nvmem_cell() 2020-09-27 14:25:48 +02:00
of of/address: Fix of_node memory leak in of_dma_is_coherent 2020-11-11 17:10:16 -06:00
opp opp: Reduce the size of critical section in _opp_table_kref_release() 2020-10-27 13:21:03 +05:30
oprofile module: Fix up module_notifier return values 2020-09-01 09:58:03 +02:00
parisc dma-mapping: split <linux/dma-mapping.h> 2020-10-06 07:07:03 +02:00
parport treewide: Use fallthrough pseudo-keyword 2020-08-23 17:36:59 -05:00
pci PCI: Fix pci_slot_release() NULL pointer dereference 2020-12-30 11:54:28 +01:00
pcmcia dma-mapping: remove DMA_MASK_NONE 2020-09-25 06:12:15 +02:00
perf perf: arm-cmn: Fix conversion specifiers for node type 2020-10-01 22:30:07 +01:00
phy drm/mediatek: avoid dereferencing a null hdmi_phy on an error message 2020-12-30 11:53:43 +01:00
pinctrl pinctrl: sunxi: Always call chained_irq_{enter, exit} in sunxi_pinctrl_irq_handler 2020-12-30 11:54:25 +01:00
platform platform/x86: intel-vbtn: Allow switch events on Acer Switch Alpha 12 2020-12-30 11:54:28 +01:00
pnp PNP: fix kernel-doc markups 2020-10-27 19:23:04 +01:00
power power: supply: bq24190_charger: fix reference leak 2020-12-30 11:53:25 +01:00
powercap Merge branch 'turbostat' of git://git.kernel.org/pub/scm/linux/kernel/git/lenb/linux 2020-11-10 10:02:31 -08:00
pps treewide: replace '---help---' in Kconfig files with 'help' 2020-06-14 01:57:21 +09:00
ps3 powerpc/ps3: use dma_mapping_error() 2020-12-30 11:53:53 +01:00
ptp ptp: clockmatrix: bug fix for idtcm_strverscmp 2020-11-25 17:24:49 -08:00
pwm pwm: sun4i: Remove erroneous else branch 2020-12-30 11:53:59 +01:00
rapidio rapidio: fix the missed put_device() for rio_mport_add_riodev 2020-10-16 11:11:22 -07:00
ras RAS/CEC: Convert to DEFINE_SHOW_ATTRIBUTE() 2020-09-25 19:05:31 +02:00
regulator regulator: axp20x: Fix DLDO2 voltage control register mask for AXP22x 2020-12-30 11:54:28 +01:00
remoteproc remoteproc: sysmon: Ensure remote notification ordering 2020-12-30 11:54:28 +01:00
reset ARM: SoC-related driver updates 2020-10-24 10:39:22 -07:00
rpmsg rpmsg updates for 5.10 2020-10-22 12:58:21 -07:00
rtc rtc: ep93xx: Fix NULL pointer dereference in ep93xx_rtc_read_time 2020-12-30 11:54:29 +01:00
s390 s390/dasd: fix list corruption of lcu list 2020-12-30 11:54:09 +01:00
sbus treewide: replace '---help---' in Kconfig files with 'help' 2020-06-14 01:57:21 +09:00
scsi scsi: lpfc: Re-fix use after free in lpfc_rq_buf_free() 2020-12-30 11:54:23 +01:00
sfi treewide: replace '---help---' in Kconfig files with 'help' 2020-06-14 01:57:21 +09:00
sh iomap: constify ioreadX() iomem argument (as in generic implementation) 2020-08-14 19:56:57 -07:00
siox siox: Use the correct style for SPDX License Identifier 2020-01-14 21:46:53 +01:00
slimbus slimbus: qcom: fix potential NULL dereference in qcom_slim_prg_slew() 2020-12-30 11:53:47 +01:00
soc soc: qcom: smp2p: Safely acquire spinlock without IRQs 2020-12-30 11:54:22 +01:00
soundwire soundwire: master: use pm_runtime_set_active() on add 2020-12-30 11:53:28 +01:00
spi spi: atmel-quadspi: Fix AHB memory accesses 2020-12-30 11:54:22 +01:00
spmi spmi: pmic-arb: Set lockdep class for hierarchical irq domains 2020-02-10 13:16:04 +01:00
ssb ssb: Remove meaningless jump label to simplify the code 2020-09-21 16:01:35 +03:00
staging staging: comedi: mf6x4: Fix AI end-of-conversion detection 2020-12-30 11:54:10 +01:00
target SCSI fixes on 20201120 2020-11-20 16:24:28 -08:00
tc The main MIPS changes for 5.6: 2020-01-31 11:28:31 -08:00
tee ARM: SoC fixes for v5.10, part 3 2020-11-27 14:48:03 -08:00
thermal thermal/drivers/cpufreq_cooling: Update cpufreq_state only if state has changed 2020-12-30 11:54:29 +01:00
thunderbolt thunderbolt: Fix use-after-free in remove_unplugged_switch() 2020-11-19 17:44:10 +03:00
tty m68k: Fix WARNING splat in pmac_zilog driver 2020-12-30 11:54:11 +01:00
uio uio: Fix use-after-free in uio_unregister_device() 2020-11-09 18:54:30 +01:00
usb USB: serial: keyspan_pda: fix write unthrottling 2020-12-30 11:54:12 +01:00
vdpa vdpa/mlx5: Use write memory barrier after updating CQ index 2020-12-30 11:54:00 +01:00
vfio vfio/pci/nvlink2: Do not attempt NPU2 setup on POWER8NVL NPU 2020-12-30 11:54:03 +01:00
vhost vhost scsi: fix error return code in vhost_scsi_set_endpoint() 2020-12-30 11:54:00 +01:00
video video: fbdev: atmel_lcdfb: fix return error code in atmel_lcdfb_of_init() 2020-12-30 11:53:13 +01:00
virt nitro_enclaves: Fixup type and simplify logic of the poll mask setup 2020-11-09 18:20:36 +01:00
virtio virtio_ring: Fix two use after free bugs 2020-12-30 11:54:00 +01:00
visorbus treewide: replace '---help---' in Kconfig files with 'help' 2020-06-14 01:57:21 +09:00
vlynq treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 102 2019-05-24 17:39:00 +02:00
vme treewide: replace '---help---' in Kconfig files with 'help' 2020-06-14 01:57:21 +09:00
w1 w1: w1_therm: make w1_poll_completion static 2020-10-05 14:49:24 +02:00
watchdog watchdog: coh901327: add COMMON_CLK dependency 2020-12-30 11:53:58 +01:00
xen xenbus/xenbus_backend: Disallow pending watch messages 2020-12-30 11:54:27 +01:00
zorro zorro: Fix address space collision message with RAM expansion boards 2020-08-26 13:26:52 +02:00
Kconfig virtio: fixes, vdpa 2020-04-08 10:51:53 -07:00
Makefile vdpa: mlx5: fix vdpa/vhost dependencies 2020-12-02 04:09:56 -05:00