diff mbox series

[v6,bpf-next,04/10] lib/buildid: remove single-page limit for PHDR search

Message ID 20240814185417.1171430-5-andrii@kernel.org (mailing list archive)
State Changes Requested
Delegated to: BPF
Headers show
Series Harden and extend ELF build ID parsing logic | expand

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netdev/series_format success Posting correctly formatted
netdev/tree_selection success Clearly marked for bpf-next, async
netdev/ynl success Generated files up to date; no warnings/errors; no diff in generated;
netdev/fixes_present success Fixes tag not required for -next series
netdev/header_inline success No static functions without inline keyword in header files
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netdev/check_selftest success No net selftest shell script
netdev/verify_fixes success No Fixes tag
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netdev/checkpatch success total: 0 errors, 0 warnings, 0 checks, 32 lines checked
netdev/build_clang_rust success No Rust files in patch. Skipping build
netdev/kdoc success Errors and warnings before: 0 this patch: 0
netdev/source_inline success Was 0 now: 0
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Commit Message

Andrii Nakryiko Aug. 14, 2024, 6:54 p.m. UTC 
Now that freader allows to access multiple pages transparently, there is
no need to limit program headers to the very first ELF file page. Remove
this limitation, but still put some sane limit on amount of program
headers that we are willing to iterate over (set arbitrarily to 256).

Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
---
 lib/buildid.c | 14 ++++++++------
 1 file changed, 8 insertions(+), 6 deletions(-)
diff mbox series

Patch

diff --git a/lib/buildid.c b/lib/buildid.c
index 7fb08a1d98bd..e8fc4aeb01f2 100644
--- a/lib/buildid.c
+++ b/lib/buildid.c
@@ -8,6 +8,8 @@ 
 
 #define BUILD_ID 3
 
+#define MAX_PHDR_CNT 256
+
 struct freader {
 	void *buf;
 	u32 buf_sz;
@@ -223,9 +225,9 @@  static int get_build_id_32(struct freader *r, unsigned char *build_id, __u32 *si
 	phnum = READ_ONCE(ehdr->e_phnum);
 	phoff = READ_ONCE(ehdr->e_phoff);
 
-	/* only supports phdr that fits in one page */
-	if (phnum > (PAGE_SIZE - sizeof(Elf32_Ehdr)) / sizeof(Elf32_Phdr))
-		return -EINVAL;
+	/* set upper bound on amount of segments (phdrs) we iterate */
+	if (phnum > MAX_PHDR_CNT)
+		phnum = MAX_PHDR_CNT;
 
 	/* check that phoff is not large enough to cause an overflow */
 	if (phoff + phnum * sizeof(Elf32_Phdr) < phoff)
@@ -260,9 +262,9 @@  static int get_build_id_64(struct freader *r, unsigned char *build_id, __u32 *si
 	phnum = READ_ONCE(ehdr->e_phnum);
 	phoff = READ_ONCE(ehdr->e_phoff);
 
-	/* only supports phdr that fits in one page */
-	if (phnum > (PAGE_SIZE - sizeof(Elf64_Ehdr)) / sizeof(Elf64_Phdr))
-		return -EINVAL;
+	/* set upper bound on amount of segments (phdrs) we iterate */
+	if (phnum > MAX_PHDR_CNT)
+		phnum = MAX_PHDR_CNT;
 
 	/* check that phoff is not large enough to cause an overflow */
 	if (phoff + phnum * sizeof(Elf64_Phdr) < phoff)