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fix: double free when getting command path for empty command

Browse source 
```
minishell$ ""
```
leads to the following error:
```
=================================================================
==1158770==ERROR: AddressSanitizer: attempting double-free on 0x5060000020c0 in thread T0:
    #0 0x5649fcb5b8a8 in free.part.0 asan_malloc_linux.cpp.o
    #1 0x5649fcbac549 in deal_with_filled_path /home/khais/src/42/common_env/minishell/src/subst/simple_filename_exp.c:119:3
    #2 0x5649fcbac38b in filepath_from_env /home/khais/src/42/common_env/minishell/src/subst/simple_filename_exp.c:165:10
    #3 0x5649fcbac220 in get_cmdpath /home/khais/src/42/common_env/minishell/src/subst/simple_filename_exp.c:186:10
    #4 0x5649fcba8664 in simple_cmd_execute /home/khais/src/42/common_env/minishell/src/executing/simple_cmd/simple_cmd_execute.c:71:8
    #5 0x5649fcba6e4c in execute_command /home/khais/src/42/common_env/minishell/src/minishell.c:49:2
    #6 0x5649fcba6ce5 in main /home/khais/src/42/common_env/minishell/src/minishell.c:92:3
    #7 0x7fb4f2dcd27d in __libc_start_call_main (/nix/store/nqb2ns2d1lahnd5ncwmn6k84qfd7vx2k-glibc-2.40-36/lib/libc.so.6+0x2a27d) (BuildId: 704cab5816f130c494208e8cc24d87a386ef085b)
    #8 0x7fb4f2dcd338 in __libc_start_main@GLIBC_2.2.5 (/nix/store/nqb2ns2d1lahnd5ncwmn6k84qfd7vx2k-glibc-2.40-36/lib/libc.so.6+0x2a338) (BuildId: 704cab5816f130c494208e8cc24d87a386ef085b)
    #9 0x5649fca6f394 in _start (/home/khais/src/42/common_env/minishell/minishell+0x2b394)

0x5060000020c0 is located 0 bytes inside of 58-byte region [0x5060000020c0,0x5060000020fa)
freed by thread T0 here:
    #0 0x5649fcb5b8a8 in free.part.0 asan_malloc_linux.cpp.o
    #1 0x5649fcbac669 in select_path /home/khais/src/42/common_env/minishell/src/subst/simple_filename_exp.c:81:3
    #2 0x5649fcbac524 in deal_with_filled_path /home/khais/src/42/common_env/minishell/src/subst/simple_filename_exp.c:116:9
    #3 0x5649fcbac38b in filepath_from_env /home/khais/src/42/common_env/minishell/src/subst/simple_filename_exp.c:165:10
    #4 0x5649fcbac220 in get_cmdpath /home/khais/src/42/common_env/minishell/src/subst/simple_filename_exp.c:186:10
    #5 0x5649fcba8664 in simple_cmd_execute /home/khais/src/42/common_env/minishell/src/executing/simple_cmd/simple_cmd_execute.c:71:8
    #6 0x5649fcba6e4c in execute_command /home/khais/src/42/common_env/minishell/src/minishell.c:49:2
    #7 0x5649fcba6ce5 in main /home/khais/src/42/common_env/minishell/src/minishell.c:92:3
    #8 0x7fb4f2dcd27d in __libc_start_call_main (/nix/store/nqb2ns2d1lahnd5ncwmn6k84qfd7vx2k-glibc-2.40-36/lib/libc.so.6+0x2a27d) (BuildId: 704cab5816f130c494208e8cc24d87a386ef085b)

previously allocated by thread T0 here:
    #0 0x5649fcb5c897 in malloc (/home/khais/src/42/common_env/minishell/minishell+0x118897)
    #1 0x5649fcbac6be in alloc_path /home/khais/src/42/common_env/minishell/src/subst/simple_filename_exp_utils.c:34:9
    #2 0x5649fcbac4e9 in deal_with_filled_path /home/khais/src/42/common_env/minishell/src/subst/simple_filename_exp.c:113:15
    #3 0x5649fcbac38b in filepath_from_env /home/khais/src/42/common_env/minishell/src/subst/simple_filename_exp.c:165:10
    #4 0x5649fcbac220 in get_cmdpath /home/khais/src/42/common_env/minishell/src/subst/simple_filename_exp.c:186:10
    #5 0x5649fcba8664 in simple_cmd_execute /home/khais/src/42/common_env/minishell/src/executing/simple_cmd/simple_cmd_execute.c:71:8
    #6 0x5649fcba6e4c in execute_command /home/khais/src/42/common_env/minishell/src/minishell.c:49:2
    #7 0x5649fcba6ce5 in main /home/khais/src/42/common_env/minishell/src/minishell.c:92:3
    #8 0x7fb4f2dcd27d in __libc_start_call_main (/nix/store/nqb2ns2d1lahnd5ncwmn6k84qfd7vx2k-glibc-2.40-36/lib/libc.so.6+0x2a27d) (BuildId: 704cab5816f130c494208e8cc24d87a386ef085b)

SUMMARY: AddressSanitizer: double-free asan_malloc_linux.cpp.o in free.part.0
==1158770==ABORTING
```

Looks like select_path frees filepath sometimes, no idea why. Removing these
lines didn't break any tests.

I'm pushing this to get a second opinion
This commit is contained in:
Khaïs COLIN 2025-04-01 18:38:31 +02:00
parent 1df6a6ad9a
commit e84b88394a
Signed by: logistic-bot
SSH key fingerprint: SHA256:RlpiqKeXpcPFZZ4y9Ou4xi2M8OhRJovIwDlbCaMsuAo
2 changed files with 8 additions and 3 deletions
Download patch file Download diff file Expand all files Collapse all files

7
test.sh
View file

@ -335,6 +335,13 @@ status=1
hello=hi
EOF
when_run <<EOF "empty command is not found"
""
EOF
expecting <<EOF
minishell: : command not found
EOF
when_run <<EOF "quoted parentheses are not operators"
echo unclosed '('
EOF