Messages in this thread Patch in this message | | | Date | Wed, 11 Oct 2023 21:46:52 -0400 | From | Rik van Riel <> | Subject | [PATCH v5] execve.2: execve also returns E2BIG if a string is too long |
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The execve syscall returns -E2BIG in 3 cases: - The total length of the command line arguments and environment is too large. - An argument or environment string (including the NUL byte) is longer than MAX_ARG_STRLEN. - The full path to the executable (including the NUL byte) exceeds MAX_ARG_STRLEN.
Spell out all 3 cases in the -E2BIG section.
Discovered by moving a too large commandline parameter to an environment variable, and finding that things still did not work. Examined the code in fs/exec.c to get the details.
This simple shell script starts failing at 2^17 on a system with 4kB page size: ./exec2big.sh: line 10: /bin/true: Argument list too long fork failed at loop 17
#!/bin/sh STRING="a"
for loop in `seq 20`; do STRING="$STRING$STRING" export STRING if /bin/true ; then : # still under the limit else echo "fork failed at loop $loop" fi done
Signed-off-by: Rik van Riel <riel@surriel.com> Suggested-by: Matthew House <mattlloydhouse@gmail.com> --- man2/execve.2 | 7 ++++++- 1 file changed, 6 insertions(+), 1 deletion(-)
diff --git a/man2/execve.2 b/man2/execve.2 index 0d9582492ad1..b689101771e5 100644 --- a/man2/execve.2 +++ b/man2/execve.2 @@ -449,7 +449,12 @@ The total number of bytes in the environment .RI ( envp ) and argument list .RI ( argv ) -is too large. +is too large, +an argument or environment string is too long, +or the full +.I pathname +of the executable is too long. +The terminating NUL is counted as part of the string length. .TP .B EACCES Search permission is denied on a component of the path prefix of -- 2.41.0
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