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Fix segfault in NUT clients with empty host/device name components #2053

Merged
merged 6 commits into from
Sep 16, 2023
Merged

Fix segfault in NUT clients with empty host/device name components #2053

merged 6 commits into from
Sep 16, 2023

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jimklimov
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Closes: #2052

The culprit was that in some libc implementations, calling strdup(NULL) causes a segfault, where such NULL can be returned by strtok() if there were no hits. Using xstrdup() introduced across NUT codebase specifically for safety checks like these turns it into a graceful failure that calling code can handle meaningfully.

See also #677 for related concerns.

@jimklimov jimklimov added bug portability We want NUT to build and run everywhere possible impacts-release-2.8.0 Issues reported against NUT release 2.8.0 (maybe vanilla or with minor packaging tweaks) impacts-release-2.7.4 Issues reported against NUT release 2.7.4 (maybe vanilla or with minor packaging tweaks) labels Sep 14, 2023
@jimklimov jimklimov added this to the 2.8.1 milestone Sep 14, 2023
@jimklimov jimklimov mentioned this pull request Sep 14, 2023
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@jimklimov
clients/upsclient.c: upscli_splitname(): add explicit checks for empt…
d2857f6 
…y upsname and/or hostname[:port] parts, to report problems as such [networkupstools#2052]

Signed-off-by: Jim Klimov <[email protected]>
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Testing:

:; make -j 20 -s && ( set -x; ./clients/upsc dev@localhost ; ./clients/upsc dev@bogushost; ./clients/upsc dev@; ./clients/upsc @host; ./clients/upsc @ )

+ ./clients/upsc dev@localhost
Error: Connection failure: Connection refused

+ ./clients/upsc dev@bogushost
Error: No such host

+ ./clients/upsc dev@
upscli_splitname: got the @ separator and then an empty hostname[:port] string
Error: invalid UPS definition.
Required format: upsname[@hostname[:port]]

+ ./clients/upsc @host
upscli_splitname: got empty upsname string
Error: invalid UPS definition.
Required format: upsname[@hostname[:port]]

+ ./clients/upsc @
upscli_splitname: got empty upsname string
Error: invalid UPS definition.
Required format: upsname[@hostname[:port]]

No more this report (from recent master) about trash going to networking name-resolver etc:

+ ./clients/upsc dev@localhost
Error: Connection failure: Connection refused

+ ./clients/upsc dev@bogushost
Error: No such host

+ ./clients/upsc dev@
upscli_splitaddr: can't parse empty string
Error: invalid UPS definition.
Required format: upsname[@hostname[:port]]

+ ./clients/upsc @host
Error: Unknown error

+ ./clients/upsc @
Segmentation fault

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jimklimov commented Sep 14, 2023 •
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Weird... a handful of builds got segfaults during make check-NIT, but in random-looking locations (gpiotest on debian, possibly upsd in Windows at https://ci.appveyor.com/project/nut-travis/nut/builds/48040434)

Gotta check if the xbasename() input-sanity fix here (and possibly those in xstrdup() etc.) misfired somehow...

@jimklimov
Revert "common/common.c: extend xbasename(), xstrdup() and xrealloc()…
05edad7 
… definition to return NULL if input was NULL (and log it) [networkupstools#2052]"

This reverts commit 05610d1.
Seems to cause segfaults on its own, maybe something relied on
older behavior (non-NULLs returned in case of bad inputs?)
To investigate separately later...
@jimklimov
common/common.c: extend xstrdup() definition to return NULL if input …
7c59cf1 
…was NULL (and log it) [networkupstools#2052]

Signed-off-by: Jim Klimov <[email protected]>
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✅ Build nut 2.8.0.749-master completed (commit 871f926afd by @jimklimov)

@jimklimov jimklimov merged commit 484ed6d into networkupstools:master Sep 16, 2023
@jimklimov jimklimov deleted the issue-2052 branch September 16, 2023 20:20
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bug impacts-release-2.7.4 Issues reported against NUT release 2.7.4 (maybe vanilla or with minor packaging tweaks) impacts-release-2.8.0 Issues reported against NUT release 2.8.0 (maybe vanilla or with minor packaging tweaks) portability We want NUT to build and run everywhere possible
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passing null values to upsc results in kernel segmentation fault
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