Fix gcc10.1 truncation error #10433

gamanakis · 2020-06-10T10:34:45Z

After commit c9e319f gcc10.1 complains with:

In file included from ../../include/sys/spa.h:44,
                 from ../../module/zfs/ddt.c:28:
../../module/zfs/ddt.c: In function ‘ddt_object_name’:
../../include/sys/dmu.h:373:24: error: ‘%s’ directive output may be truncated writing up to 95 bytes into a region of size 75 [-Werror=format-truncation=]
  373 | #define DMU_POOL_DDT   "DDT-%s-%s-%s"
      |                        ^~~~~~~~~~~~~~
../../module/zfs/ddt.c:256:37: note: in expansion of macro ‘DMU_POOL_DDT’
  256 |  (void) snprintf(name, DDT_NAMELEN, DMU_POOL_DDT,
      |                                     ^~~~~~~~~~~~
../../include/sys/dmu.h:373:32: note: format string is defined here
  373 | #define DMU_POOL_DDT   "DDT-%s-%s-%s"
      |                                ^~
../../module/zfs/ddt.c:256:9: note: ‘snprintf’ output 7 or more bytes (assuming 102) into a destination of size 80
  256 |  (void) snprintf(name, DDT_NAMELEN, DMU_POOL_DDT,
      |         ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
  257 |      zio_checksum_table[ddt->ddt_checksum].ci_name,
      |      ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
  258 |      ddt_ops[type]->ddt_op_name, ddt_class_name[class]);
      |      ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

Increasing DTT_NAMELEN fixes it.

Signed-off-by: George Amanakis gamanakis@gmail.com

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Types of changes

Bug fix (non-breaking change which fixes an issue)
New feature (non-breaking change which adds functionality)
Performance enhancement (non-breaking change which improves efficiency)
Code cleanup (non-breaking change which makes code smaller or more readable)
Breaking change (fix or feature that would cause existing functionality to change)
Documentation (a change to man pages or other documentation)

Checklist:

My code follows the ZFS on Linux code style requirements.
I have updated the documentation accordingly.
I have read the contributing document.
I have added tests to cover my changes.
I have run the ZFS Test Suite with this change applied.
All commit messages are properly formatted and contain Signed-off-by.

gcc10.1 complains with: ../../include/sys/dmu.h:373:24: error: ‘%s’ directive output may be truncated writing up to 95 bytes into a region of size 75 [-Werror=format-truncation=] 373 | #define DMU_POOL_DDT "DDT-%s-%s-%s" | ^~~~~~~~~~~~~~ ../../module/zfs/ddt.c:256:37: note: in expansion of macro ‘DMU_POOL_DDT’ 256 | (void) snprintf(name, DDT_NAMELEN, DMU_POOL_DDT, | ^~~~~~~~~~~~ ../../include/sys/dmu.h:373:32: note: format string is defined here 373 | #define DMU_POOL_DDT "DDT-%s-%s-%s" | ^~ ../../module/zfs/ddt.c:256:9: note: ‘snprintf’ output 7 or more bytes (assuming 102) into a destination of size 80 256 | (void) snprintf(name, DDT_NAMELEN, DMU_POOL_DDT, | ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ 257 | zio_checksum_table[ddt->ddt_checksum].ci_name, | ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ 258 | ddt_ops[type]->ddt_op_name, ddt_class_name[class]); | ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Increasing DTT_NAMELEN fixes it. Signed-off-by: George Amanakis <gamanakis@gmail.com>

codecov · 2020-06-10T17:43:57Z

Codecov Report

Merging #10433 into master will increase coverage by 0.12%.
The diff coverage is n/a.

@@            Coverage Diff             @@
##           master   #10433      +/-   ##
==========================================
+ Coverage   79.46%   79.59%   +0.12%     
==========================================
  Files         391      391              
  Lines      123866   123866              
==========================================
+ Hits        98433    98585     +152     
+ Misses      25433    25281     -152

Flag	Coverage Δ
#kernel	`80.02% <ø> (-0.01%)`	⬇️
#user	`66.08% <ø> (+0.46%)`	⬆️

Impacted Files	Coverage Δ
module/lua/lmem.c	`83.33% <0.00%> (-4.17%)`	⬇️
module/icp/algs/modes/gcm.c	`79.25% <0.00%> (-2.56%)`	⬇️
module/os/linux/zfs/zio_crypt.c	`79.97% <0.00%> (-1.23%)`	⬇️
module/zfs/vdev_mirror.c	`94.77% <0.00%> (-1.12%)`	⬇️
module/os/linux/spl/spl-kmem-cache.c	`83.72% <0.00%> (-1.09%)`	⬇️
module/zfs/dmu_traverse.c	`95.68% <0.00%> (-1.00%)`	⬇️
module/os/linux/zfs/zfs_vnops.c	`69.47% <0.00%> (-0.58%)`	⬇️
module/icp/api/kcf_mac.c	`38.28% <0.00%> (-0.58%)`	⬇️
module/zfs/vdev_indirect_mapping.c	`98.55% <0.00%> (-0.49%)`	⬇️
module/zfs/arc.c	`88.91% <0.00%> (-0.46%)`	⬇️
... and 54 more

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behlendorf

Increasing the buffer size to silence the warning is fine. But looking at the code I don't see how it determined 102 bytes was the worst case, 80 looks like it should be sufficient for all cases.

gamanakis · 2020-06-10T19:14:12Z

That eludes me right now too.

gcc10.1 complains with: ../../include/sys/dmu.h:373:24: error: ‘%s’ directive output may be truncated writing up to 95 bytes into a region of size 75 [-Werror=format-truncation=] 373 | #define DMU_POOL_DDT "DDT-%s-%s-%s" | ^~~~~~~~~~~~~~ ../../module/zfs/ddt.c:256:37: note: in expansion of macro ‘DMU_POOL_DDT’ 256 | (void) snprintf(name, DDT_NAMELEN, DMU_POOL_DDT, | ^~~~~~~~~~~~ ../../include/sys/dmu.h:373:32: note: format string is defined here 373 | #define DMU_POOL_DDT "DDT-%s-%s-%s" | ^~ ../../module/zfs/ddt.c:256:9: note: ‘snprintf’ output 7 or more bytes (assuming 102) into a destination of size 80 256 | (void) snprintf(name, DDT_NAMELEN, DMU_POOL_DDT, | ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ 257 | zio_checksum_table[ddt->ddt_checksum].ci_name, | ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ 258 | ddt_ops[type]->ddt_op_name, ddt_class_name[class]); | ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Increasing DTT_NAMELEN fixes it. Reviewed-By: Brian Behlendorf <behlendorf1@llnl.gov> Signed-off-by: George Amanakis <gamanakis@gmail.com> Closes #10433

gcc10.1 complains with: ../../include/sys/dmu.h:373:24: error: ‘%s’ directive output may be truncated writing up to 95 bytes into a region of size 75 [-Werror=format-truncation=] 373 | #define DMU_POOL_DDT "DDT-%s-%s-%s" | ^~~~~~~~~~~~~~ ../../module/zfs/ddt.c:256:37: note: in expansion of macro ‘DMU_POOL_DDT’ 256 | (void) snprintf(name, DDT_NAMELEN, DMU_POOL_DDT, | ^~~~~~~~~~~~ ../../include/sys/dmu.h:373:32: note: format string is defined here 373 | #define DMU_POOL_DDT "DDT-%s-%s-%s" | ^~ ../../module/zfs/ddt.c:256:9: note: ‘snprintf’ output 7 or more bytes (assuming 102) into a destination of size 80 256 | (void) snprintf(name, DDT_NAMELEN, DMU_POOL_DDT, | ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ 257 | zio_checksum_table[ddt->ddt_checksum].ci_name, | ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ 258 | ddt_ops[type]->ddt_op_name, ddt_class_name[class]); | ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Increasing DTT_NAMELEN fixes it. Reviewed-By: Brian Behlendorf <behlendorf1@llnl.gov> Signed-off-by: George Amanakis <gamanakis@gmail.com> Closes openzfs#10433 (cherry picked from commit f2edc00)

gcc10.1 complains with: ../../include/sys/dmu.h:373:24: error: ‘%s’ directive output may be truncated writing up to 95 bytes into a region of size 75 [-Werror=format-truncation=] 373 | #define DMU_POOL_DDT "DDT-%s-%s-%s" | ^~~~~~~~~~~~~~ ../../module/zfs/ddt.c:256:37: note: in expansion of macro ‘DMU_POOL_DDT’ 256 | (void) snprintf(name, DDT_NAMELEN, DMU_POOL_DDT, | ^~~~~~~~~~~~ ../../include/sys/dmu.h:373:32: note: format string is defined here 373 | #define DMU_POOL_DDT "DDT-%s-%s-%s" | ^~ ../../module/zfs/ddt.c:256:9: note: ‘snprintf’ output 7 or more bytes (assuming 102) into a destination of size 80 256 | (void) snprintf(name, DDT_NAMELEN, DMU_POOL_DDT, | ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ 257 | zio_checksum_table[ddt->ddt_checksum].ci_name, | ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ 258 | ddt_ops[type]->ddt_op_name, ddt_class_name[class]); | ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Increasing DTT_NAMELEN fixes it. Reviewed-By: Brian Behlendorf <behlendorf1@llnl.gov> Signed-off-by: George Amanakis <gamanakis@gmail.com> Closes openzfs#10433

gamanakis force-pushed the gcc10_fix2 branch from 9cce6ef to c35b052 Compare June 10, 2020 10:36

behlendorf added the Status: Code Review Needed Ready for review and testing label Jun 10, 2020

behlendorf requested a review from lundman June 10, 2020 17:58

behlendorf approved these changes Jun 10, 2020

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behlendorf added Status: Accepted Ready to integrate (reviewed, tested) and removed Status: Code Review Needed Ready for review and testing labels Jun 11, 2020

behlendorf merged commit f2edc00 into openzfs:master Jun 13, 2020

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Fix gcc10.1 truncation error #10433

Fix gcc10.1 truncation error #10433

gamanakis commented Jun 10, 2020 •

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codecov bot commented Jun 10, 2020 •

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gamanakis commented Jun 10, 2020

Fix gcc10.1 truncation error #10433

Fix gcc10.1 truncation error #10433

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gamanakis commented Jun 10, 2020 • edited Loading

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Checklist:

codecov bot commented Jun 10, 2020 • edited Loading

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gamanakis commented Jun 10, 2020

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